This is happening only since last update (or one in the last day or so). Seeing it on multiple sites, and quit => reopen didn't work, nor did a restart.
EDIT: As pointed out by @Anthony, this appears to be a dupe of this report, but since that's marked status-completed, it might be a different bug causing the same output? I'm happy to self-close as dupe, but want to make sure we ID the new cause.