Block display issue

I have a possible bug that I’ve spotted on several sites when using Reusable Blocks. I’ve indicated one in the link above. The link above is to a WordPress.com site but I’ve seen this on a www.remarpro.com site as well.

When a reuseable block is removed using the “remove block” command, a rectangle with a plus in it remains. When the post is seen via preview, the content of the reusable block (that was supposably removed) is still present. If the block with the plus is clicked on and removed again, the odd looking block as well as the content is removed.
I have screenshots of the above.
Any ideas of if this can be added to the “bug” list?

The page I need help with: [log in to see the link]