picking thumbnails

I suspect that there is a problem with picking thumbnails.

I have a large number of clips that are waiting for submission, because I want the thumbnail to be updated before I submit it.

for many of these clips, I re-select the thumbnail once or twice a day and they are not updating. many days have gone by.

however, for 2 of them, they updated within 30 minutes or so.

so 2 worked after a short delay, and another 30 to 50 are waiting for days, with no updates.

I am going to use the example with this clip id:

37267748

I uploaded it April 19, 4 days ago. because I know there is a lag to regenerate the thumbnail, I usually go through all of my new uploads right away and select the thumbnails.

every day, many times a day, I am checking the clips to submit them, and 4 days have passed, and the thumbnail still has not updated. I have probably applied the thumbnail change 4 or 5 times by now to this clip, and still no change (I just did it again).