Problems Deleting Reusable Blocks

I have been using a set of reusable blocks as headers for a long time. In the past, when I wanted to delete the block, I would use ctrl-alt-z and get rid of it on the post without affecting the saved code that displays on many other pages.
Recently, though, the behavior of my reusable blocks has changed.
When I attempt to delete the reusable block, it changed it to a slip editor-wide box with a plus in the middle. If I delete a non-reusable block, it is just gone.
When I go do save, though, it now asks me to save the reusable block, and will overwrite the code with blank space now.
When I click on a reusable block, it almost looks like it is nested or expands it. I haven’t seen that behavior before. It opens up a small section of with space in a border under the code (the blocks are html code), with a plus on the far right.
Anyone know what is going on?
Thanks in advance.
Jeff