source/blender/gpu/metal/mtl_state.mm

@@ -579,6 +579,10 @@ void MTLStateManager::issue_barrier(eGPUBarrier barrier_bits)
   BLI_assert(ctx);
 
   ctx->main_command_buffer.insert_memory_barrier(barrier_bits, before_stages, after_stages);
+
+  if (barrier_bits & GPU_BARRIER_BUFFER_UPDATE) {
+    GPU_finish();
+  }
 }
 
 MTLFence::~MTLFence()

source/blender/gpu/metal/mtl_storage_buffer.mm

@@ -426,16 +426,13 @@ void MTLStorageBuf::read(void *data)
   else {
     /** Direct storage buffer read. */
     /* If we have a synchronization event from a prior memory sync, ensure memory is fully synced.
-     * Otherwise, assume read is synchronous and stall until in-flight work is complete. */
+     * Otherwise, assume read is asynchronous. */
     if (gpu_write_fence_ != nil) {
       /* Ensure the GPU updates are visible to the host before reading. */
       while (gpu_write_fence_.signaledValue < host_read_signal_value_) {
         BLI_time_sleep_ms(1);
       }
     }
-    else {
-      GPU_finish();
-    }
 
     /* Managed buffers need to be explicitly flushed back to host. */
     if (metal_buffer_->get_resource_options() & MTLResourceStorageModeManaged) {