diff --git a/javascript/progressBar.js b/javascript/progressBar.js
index afb9259dc..3f5c9fcef 100644
--- a/javascript/progressBar.js
+++ b/javascript/progressBar.js
@@ -61,8 +61,8 @@ function randomId() {
 function requestProgress(id_task, progressEl, galleryEl, atEnd = null, onProgress = null, once = false) {
   localStorage.setItem('task', id_task);
   let hasStarted = false;
-  const dateStart = new Date();
-  const prevProgress = null;
+  let dateStart = new Date();
+  let prevProgress = null;
   const parentGallery = galleryEl ? galleryEl.parentNode : null;
   let livePreview;
   let img;
@@ -113,30 +113,36 @@ function requestProgress(id_task, progressEl, galleryEl, atEnd = null, onProgres
     if (!opts.live_previews_enable || opts.live_preview_refresh_period === 0 || opts.show_progress_every_n_steps === 0) return;
 
     const onProgressHandler = (res) => {
-      // debug('onProgress', res);
+      if (res?.debug) debug('livePreview:', dateStart, res);
       lastState = res;
       const elapsedFromStart = (new Date() - dateStart) / 1000;
       hasStarted |= res.active;
       if (res.completed || (!res.active && (hasStarted || once)) || (elapsedFromStart > 30 && !res.queued && res.progress === prevProgress)) {
-        // debug('onProgressEnd', res);
+        if (res?.debug) debug('livePreview end:', res);
         done();
         return;
       }
+      if (res.progress !== prevProgress) {
+        dateStart = new Date();
+        prevProgress = res.progress;
+      }
       setProgress(res);
       if (res.live_preview && !livePreview) initLivePreview();
       if (res.live_preview && galleryEl) {
         if (img.src !== res.live_preview) img.src = res.live_preview;
+        id_live_preview = res.id_live_preview;
       }
       if (onProgress) onProgress(res);
       setTimeout(() => start(id_task, id_live_preview), opts.live_preview_refresh_period || 500);
     };
 
     const onProgressErrorHandler = (err) => {
-      error(`onProgressError: ${err}`);
+      error(`livePreview: ${err}`);
       done();
     };
 
     xhrPost('./internal/progress', { id_task, id_live_preview }, onProgressHandler, onProgressErrorHandler, false, 5000);
   };
+  debug('livePreview start:', dateStart);
   start(id_task, 0);
 }
diff --git a/modules/progress.py b/modules/progress.py
index d18d1ee9f..68102b915 100644
--- a/modules/progress.py
+++ b/modules/progress.py
@@ -1,4 +1,5 @@
 import base64
+import os
 import io
 import time
 from pydantic import BaseModel, Field # pylint: disable=no-name-in-module
@@ -10,6 +11,8 @@ pending_tasks = {}
 finished_tasks = []
 recorded_results = []
 recorded_results_limit = 2
+debug = os.environ.get('SD_PREVIEW_DEBUG', None) is not None
+debug_log = shared.log.trace if debug else lambda *args, **kwargs: None
 
 
 def start_task(id_task):
@@ -48,6 +51,7 @@ class InternalProgressResponse(BaseModel):
     queued: bool = Field(title="Whether the task is in queue")
     paused: bool = Field(title="Whether the task is paused")
     completed: bool = Field(title="Whether the task has already finished")
+    debug: bool = Field(title="Debug logging level")
     progress: float = Field(default=None, title="Progress", description="The progress with a range of 0 to 1")
     eta: float = Field(default=None, title="ETA in secs")
     live_preview: str = Field(default=None, title="Live preview image", description="Current live preview; a data: uri")
@@ -60,8 +64,6 @@ def progressapi(req: ProgressRequest):
     queued = req.id_task in pending_tasks
     completed = req.id_task in finished_tasks
     paused = shared.state.paused
-    if not active:
-        return InternalProgressResponse(job=shared.state.job, active=active, queued=queued, paused=paused, completed=completed, id_live_preview=-1, textinfo="Queued..." if queued else "Waiting...")
     shared.state.job_count = max(shared.state.frame_count, shared.state.job_count, shared.state.job_no)
     batch_x = max(shared.state.job_no, 0)
     batch_y = max(shared.state.job_count, 1)
@@ -75,14 +77,17 @@ def progressapi(req: ProgressRequest):
     eta = predicted - elapsed if predicted is not None else None
     id_live_preview = req.id_live_preview
     live_preview = None
-    shared.state.set_current_image()
-    if shared.opts.live_previews_enable and (shared.state.id_live_preview != req.id_live_preview) and (shared.state.current_image is not None):
+    updated = shared.state.set_current_image()
+    debug_log(f'Preview: job={shared.state.job} active={active} progress={current}/{total} request={id_live_preview} last={shared.state.id_live_preview} enabled={shared.opts.live_previews_enable} updated={updated} image={shared.state.current_image} elapsed={elapsed:.3f}')
+    if not active:
+        return InternalProgressResponse(job=shared.state.job, active=active, queued=queued, paused=paused, completed=completed, id_live_preview=-1, debug=debug, textinfo="Queued..." if queued else "Waiting...")
+    if shared.opts.live_previews_enable and (shared.state.id_live_preview != id_live_preview) and (shared.state.current_image is not None):
         buffered = io.BytesIO()
         shared.state.current_image.save(buffered, format='jpeg')
         live_preview = f'data:image/jpeg;base64,{base64.b64encode(buffered.getvalue()).decode("ascii")}'
-        id_live_preview = shared.state.id_live_preview
+    id_live_preview = shared.state.id_live_preview
 
-    res = InternalProgressResponse(job=shared.state.job, active=active, queued=queued, paused=paused, completed=completed, progress=progress, eta=eta, live_preview=live_preview, id_live_preview=id_live_preview, textinfo=shared.state.textinfo)
+    res = InternalProgressResponse(job=shared.state.job, active=active, queued=queued, paused=paused, completed=completed, progress=progress, eta=eta, live_preview=live_preview, id_live_preview=id_live_preview, debug=debug, textinfo=shared.state.textinfo)
     return res
 
 
diff --git a/modules/shared_state.py b/modules/shared_state.py
index 024427f09..3fe0279f1 100644
--- a/modules/shared_state.py
+++ b/modules/shared_state.py
@@ -149,16 +149,17 @@ class State:
 
     def set_current_image(self):
         if self.job == 'VAE': # avoid generating preview while vae is running
-            return
+            return False
         from modules.shared import opts, cmd_opts
-        if cmd_opts.lowvram or self.api or not opts.live_previews_enable or opts.show_progress_every_n_steps <= 0:
-            return
-        if not self.disable_preview and (abs(self.sampling_step - self.current_image_sampling_step) >= opts.show_progress_every_n_steps):
-            self.do_set_current_image()
+        if cmd_opts.lowvram or self.api or (not opts.live_previews_enable) or (opts.show_progress_every_n_steps <= 0):
+            return False
+        if (not self.disable_preview) and (abs(self.sampling_step - self.current_image_sampling_step) >= opts.show_progress_every_n_steps):
+            return self.do_set_current_image()
+        return False
 
     def do_set_current_image(self):
-        if self.current_latent is None or self.disable_preview or self.preview_busy:
-            return
+        if (self.current_latent is None) or self.disable_preview or self.preview_busy:
+            return False
         from modules import shared, sd_samplers
         self.preview_busy = True
         try:
@@ -175,10 +176,13 @@ class State:
             """
             image = sd_samplers.samples_to_image_grid(sample) if shared.opts.show_progress_grid else sd_samplers.sample_to_image(sample)
             self.assign_current_image(image)
+            self.preview_busy = False
+            return True
         except Exception as e:
+            self.preview_busy = False
             log.error(f'State image: last={self.id_live_preview} step={self.sampling_step} {e}')
             display(e, 'State image')
-        self.preview_busy = False
+            return False
 
     def assign_current_image(self, image):
         self.current_image = image