"Bold wrapper" tag appears after adding masonry bric

This bug has happened twice in the last 24 hours: I add a masonry bric, and fill it with images. At some later point in time I suddenly can’t edit any of the images I added.

A “Bold Wrapper” tag appears on top of the masonry bric. The blue outline for this tag extends extends outside of the bloc containing the masonry bric.

At this point, the only thing I can do is delete the entire Bloc and start over again. I’ve done this twice so far, and this “bold wrapper” just keeps coming back.