Remaining in "Waiting to Start"

Sometimes it takes over 30 minutes from when it stops at "Waiting to Start" until a system error occurs.

During normal generation, you can cancel, which is fine, but during upscaling, the "Cancel" button doesn't appear, so you have to wait indefinitely. This is problematic because you can't generate the next image until it finishes. I can wait if it happens once a day, but today is the third time. Time is precious, so please fix this as soon as possible.

Screenshots might not show the issue clearly, so please check the generation workspace (current time: 13:25).

Note: This issue persisted for a while (about a month) a long time ago. It had been fine until recently, but the symptoms have returned.