Same here - it takes 3 or 4 times for the thumbnail to stick.
You're lucky, it takes me 8 to 10 edits for the thumbnail to show correctly. So frustrating!!!
This works for me, I'm not sure if it will work for you, you may give it a try. Just edit it once, save, and leave. Come back in an hour or so. The thumbnail should be displaying properly in the way you edited it. I did this for like 10 listings in a row, and it worked for me. I used to edit it multiple times too and was so frustrated. So I basically just gave up and left. Then to my surprise, all those thumbnails turned out good after some time.
I will give that a try next time!
#1 has been broken for years.
#2 and #3 - try making the display bigger or smaller with the control key and + sign at the same time (or control minus sign). This will adjust things so they aren't so irritating.
Didnt have any trouble with it all these years until yesterday.
Had to get items back out and retake pics to try and get the whole item in the thumbnail.
It kept cutting the top parts off of the 4 things I listed.
Hopes its better today as I need to list some vintage!
Sigh.