Pasted Attribute disappears

Another month, another quirk from Bizarro World.

For some reason a former employee exploded revision note blocks. It's a triangle with a number inside, and the number is supposed to be an attribute. He would explode the block and change the attribute value as needed. Bizarre.

This morning I needed to cut&paste a revised detail. Instead of erasing the revision note before the operation, I figured I could erase it after. I pasted the detail as a block and erased the attribute inside the block. It's still visible outside the block in paper space, it can be selected (which selects the entire block), it's listed under the block's properties, and a Purge doesn't remove the layer (it's the only thing on its layer). So it's there. However, it can't be edited in place, it's not visible or selectable in the block editor, and AttSync doesn't recognize it (there are no other attributes). So it's not there.

Moral: don't Paste As Block if you have a loose attribute on the clipboard. Yes, I could explode the block and redefine it. LayDel does the job more easily.