Additional Information:
Wordpress WordPress 6.5.3, MB 5.9.5 and MB AIO 1.25.0 (Bricks, ACSS, Fluent Forms, WPStaging +)
I checked my php.ini and max_input_vars is set to 10000 and max_post_size is 256M, the php version is 8.2. I increased vars to 100000 and size to 512M. I left PHP the same. No changes in behavior.
I was not using sanitation on any of the image fields. Is that required?
Tried a different Field Set**
Image field: For an existing field, I set sanitation to "none". Still the thumbnail does not appear after update on an existing post with existing input.
Image Advanced: I added this field to a different field set and set santiation to "none". The select button does not appear at all!
Staging Site
I set up a staging site, activated twenty-twenty-four theme, and turned off all plugins except for Metabox 5.9.8 and Metabox AIO 1.26.3 (I updated here to see if it was the version I had).
Using the same field set as above**, images are not visible after update on a new post.
Inputs on existing image fields (existing posts) do not show and Add buttons do not appear.
Let me know if you need access to the staging site to look at this issue.