Moving a reusable block made of multiple blocks deletes blocks one by one

[mtias]

Create a reusable block composed of more than one block. When attempting to move the whole group, instead of moving the last block is removed until the group is empty.

(Saving the post and reloading makes the issue go away.)

[senadir]

This was only introduced recently since I couldn't reproduce before refreshing my master

It only happens to newly created reusable blocks, if you save the block, and then insert it from the inserter it doesn't happen, if save & reload, it doesn't happen as well

I added some gifs
if you insert or reload:

if you create it and try to move it:

[paaljoachim]

Btw: "Try refactoring the reusable blocks to use a separate block editor."
This PR consolidates multiple issues.
#14367
It is important to get the above PR merged. I do believe it will help with multiple issues.

Here is another Reusable block error issue:
#17217