Subsite images do not load after Update to WP5.8 or subsequent updates

@threadi No, the issue is not genuinely resolved. (More below.) I tried the suggestions at https://wordpress.org/support/topic/multisite-images-dont-load-due-to-url-change/ because my issue *appears* to be precisely the same.

I was in the process of switching servers. I was checking sites on the original server to ensure they worked, but images on SabbathIssues.org were missing. There were a number of glitches in the setup, and that’s why I’m just now getting back to this.

Although most of the images now appear, the issues are not fully fixed, and I have the same issue on another site. A server support person implemented what he called a “band-aid solution.” When I asked what he did, he wrote that he set up a redirect. Since he was going beyond the call of duty in doing this, I didn’t ask for more details. I assumed he set up a redirect in the .htaccess file, but I can’t find it there.

In fact, I cannot find a redirect re the images anywhere in my WordPress setup.

I’m thinking that if we can figure out why most, but not all of the images load on this site, perhaps I can fix the other sites with similar problems.

Keep in mind the following:
In an earlier attempt to fix the missing images issue, I uploaded 2012 and 2013 images to both the /public_html/wp-content/blogs.dir/12/files directory AND the /public_html/wp-content/sabbathissues/files directories.

I re-uploaded some images in 2023 and 2024, and they did not show up either.

Here is a post in which neither the “feature image” nor the main image/banner header show up: https://sabbathissues.org/eden-day-line-theory/ It is still the same issue as before the “band-aid” by server support:

The images show up in the Media Library as blank boxes. However, they show up perfectly in “Edit” mode inside the library. “Editing” and saving makes no difference re visibility. (The other images magically reappeared after the “band-aid” fix. I think I will have to see if I can get a more precise answer re the fix.)

If you click the space for the main image (blank on top left), you will see a badly distorted version of the image that belongs there. But it shows up beautifully in the “Edit” mode in the library.

I tried creating new posts and uploading images, but I get the same results of missing images after I upload an image.

This post has a different issue re images: The images show up fine in the post. However, the “feature image” that is supposed to show up on the front page does not show up. Furthermore, clicking on the images (which should lead to the attachment page) yields a 404 error.

I figure that the differences between the posts that show images and those that don’t might offer a clue as to what happened.

Thank you very much for this! I will work on it.

[Later] Ouch! That didn’t seem to work. But I think you are correct in that it is a thumbnail issue. Unfortunately, I *lost* some thumbnails after specifying to “Regenerate featured Image thumbnails only.”
I checked the server to see where they are stored:
They are not at https://public_html/wp-content/blogs.dir/12/files/2024/02
They are not in alternate directories I created: https://ssnet.org/public_html/wp-content/sabbathissues/files (no 2024/02 directory there)
https://ssnet.org/public_html/sabbathissues/files (no 2024/02 directory there)

There’s another issue with the second instance which I failed to post: https://sabbathissues.org/leauvaa-uta-church-members-continue-meet-sabbaths-opposition/ This post has a different issue re images: The images show up fine in the post. But clicking on the visible images (which should lead to the attachment page) yields a 404 error (Sorry, no such page).

Am checking on more options. Sure would appreciate more help!