Setting Featured Image Resets Custom Sizes in Image Blocks

[ChrissiePollock]

When I added three images separately using /image and set sizes on them, they stayed the same, even in preview, but as soon as I added the Featured Image, all the custom sizes were removed.

Steps to reproduce

1. Create a post.
2. Add an image block and pull in an image from the media library - I used /image.
3. In the Block Settings, change the Width (or height and width).
4. Check in Preview.
5. Go back to draft and see the custom dimensions are there.
6. Add a Featured Image.
7. Notice all custom sizes are reset and no longer showing.

Edited to add that the initial reporter lost custom dimensions when adding more images. I could not replicate that, but I could by adding a Featured Image.

What I expected

All my custom sizes in the blocks to remain.

What happened instead

The settings were missing.

Browser / OS version

Firefox on MacBook Pro

Screenshot / Video

This is the kicker. I totally replicated the issue, but when I went to report it, I could not replicate it. I tried by adding height, adding width and height, initially came up with the error on a site on a free plan, but it was initially reported from a site on the Premium plan. I also tested on a Premium site and tried linking to media files and not and also tested on a Premium plan test site with the same theme as the reporter, but could not replicate any more.

My screencasts are in the response to the user report, but they don't demonstrate the issue.
#user-report from #1677915-zen

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[Aurorum]

This seems to be a duplicate of #29557.

[KristinaKay]

The user came back and added a video. #1677915-zen

[brezocordero]

I am closing the issue, fixed here #29557
Customer that reported it has been notified.

[arcangelinis]

This issue may not be fully resolved. Here is what I am seeing.

1. With other Galleries added to the page, create a new Gallery.
2. Select Media Library and add images.
3. Observe the images being removed from all other galleries.

GIF

#1708591-zen

[gwwar]

@arcangelinis do you mind filing a new issue with steps? see also:
p58i-7CN-p2

In a lot of cases it's better to open a fresh one with specific steps if we missed a case. It makes it much clearer to read and fix.

[Aurorum]

That might also be another scenario of #30104.