Same!
The same thing is happening to me.
Only 4 of my 9 screenshots are now showing. I uploaded them again and when I try to add them via asset library it says "An error has occurred. Try again later."
Try and upload and says "5.png—An error occurred during upload."
Apple Watch screenshots won't let any upload or be added.
The new banner is MIA, but when you preview it you see it then when you close the preview you see the image until you go somewhere else and back.
Things are definitely broken right now in App Store Connect.
Topic:
App Store Distribution & Marketing
SubTopic:
App Store Connect
Tags: