diff --git a/src/libslic3r/SLAPrint.cpp b/src/libslic3r/SLAPrint.cpp
index d81498916..3a08cddf1 100644
--- a/src/libslic3r/SLAPrint.cpp
+++ b/src/libslic3r/SLAPrint.cpp
@@ -415,49 +415,73 @@ void SLAPrint::set_task(const TaskParams &params)
 		n_object_steps = (int)slaposCount;
 
 	if (params.single_model_object.valid()) {
+        // Find the print object to be processed with priority.
 		SLAPrintObject *print_object = nullptr;
 		size_t          idx_print_object = 0;
-		for (; idx_print_object < m_objects.size(); ++idx_print_object)
+		for (; idx_print_object < m_objects.size(); ++ idx_print_object)
 			if (m_objects[idx_print_object]->model_object()->id() == params.single_model_object) {
 				print_object = m_objects[idx_print_object];
 				break;
 			}
 		assert(print_object != nullptr);
-		bool shall_cancel = false;
-		for (int istep = 0; istep < n_object_steps; ++istep)
-			if (! print_object->m_stepmask[istep]) {
-				shall_cancel = true;
+        // Find out whether the priority print object is being currently processed.
+        bool running = false;
+		for (int istep = 0; istep < n_object_steps; ++ istep) {
+			if (! print_object->m_stepmask[istep])
+                // Step was skipped, cancel.
+				break;
+			if (print_object->is_step_started_unguarded(SLAPrintObjectStep(istep))) {
+                // No step was skipped, and a wanted step is being processed. Don't cancel.
+				running = true;
 				break;
 			}
-		bool running = false;
-		if (!shall_cancel) {
-			for (int istep = 0; istep < n_object_steps; ++ istep)
-				if (print_object->is_step_started_unguarded(SLAPrintObjectStep(istep))) {
-					running = true;
-					break;
-				}
 		}
-		if (!running)
+		if (! running)
 			this->call_cancel_callback();
 
 		// Now the background process is either stopped, or it is inside one of the print object steps to be calculated anyway.
 		if (params.single_model_instance_only) {
 			// Suppress all the steps of other instances.
 			for (SLAPrintObject *po : m_objects)
-				for (int istep = 0; istep < (int)slaposCount; ++istep)
+				for (int istep = 0; istep < (int)slaposCount; ++ istep)
 					po->m_stepmask[istep] = false;
-		}
-		else if (!running) {
+		} else if (! running) {
 			// Swap the print objects, so that the selected print_object is first in the row.
 			// At this point the background processing must be stopped, so it is safe to shuffle print objects.
 			if (idx_print_object != 0)
 				std::swap(m_objects.front(), m_objects[idx_print_object]);
 		}
+        // and set the steps for the current object.
 		for (int istep = 0; istep < n_object_steps; ++ istep)
 			print_object->m_stepmask[istep] = true;
-		for (int istep = n_object_steps; istep < (int)slaposCount; ++istep)
+		for (int istep = n_object_steps; istep < (int)slaposCount; ++ istep)
 			print_object->m_stepmask[istep] = false;
-	}
+	} else {
+        // Slicing all objects.
+        bool running = false;
+        for (SLAPrintObject *print_object : m_objects)
+            for (int istep = 0; istep < n_object_steps; ++ istep) {
+                if (! print_object->m_stepmask[istep]) {
+                    // Step may have been skipped. Restart.
+                    goto loop_end;
+                }
+                if (print_object->is_step_started_unguarded(SLAPrintObjectStep(istep))) {
+                    // This step is running, and the state cannot be changed due to the this->state_mutex() being locked.
+                    // It is safe to manipulate m_stepmask of other SLAPrintObjects and SLAPrint now.
+                    running = true;
+                    goto loop_end;
+                }
+            }
+    loop_end:
+        if (! running)
+            this->call_cancel_callback();
+        for (SLAPrintObject *po : m_objects) {
+            for (int istep = 0; istep < n_object_steps; ++ istep)
+                po->m_stepmask[istep] = true;
+            for (int istep = n_object_steps; istep < (int)slaposCount; ++ istep)
+                po->m_stepmask[istep] = false;
+        }
+    }
 
     if (params.to_object_step != -1 || params.to_print_step != -1) {
         // Limit the print steps.
diff --git a/src/slic3r/GUI/Plater.cpp b/src/slic3r/GUI/Plater.cpp
index 28b3008fd..c368c4a07 100644
--- a/src/slic3r/GUI/Plater.cpp
+++ b/src/slic3r/GUI/Plater.cpp
@@ -2142,6 +2142,8 @@ void Plater::priv::export_gcode(fs::path output_path, PrintHostJob upload_job)
         background_process.schedule_upload(std::move(upload_job));
     }
 
+    // If the SLA processing of just a single object's supports is running, restart slicing for the whole object.
+    this->background_process.set_task(PrintBase::TaskParams());
     this->restart_background_process(priv::UPDATE_BACKGROUND_PROCESS_FORCE_EXPORT);
 }
 
@@ -3068,6 +3070,8 @@ void Plater::reslice()
     unsigned int state = this->p->update_background_process(true);
     if (state & priv::UPDATE_BACKGROUND_PROCESS_REFRESH_SCENE)
         this->p->view3D->reload_scene(false);
+    // If the SLA processing of just a single object's supports is running, restart slicing for the whole object.
+    this->p->background_process.set_task(PrintBase::TaskParams());
     // Only restarts if the state is valid.
     this->p->restart_background_process(state | priv::UPDATE_BACKGROUND_PROCESS_FORCE_RESTART);
 }