Has anyone else experienced "Removed unused widget" on widgets that were very much in use?

I don’t have a clue what happened, I just loaded up the project I have been working on, hit play to refresh myself with what needed work, and got compiler error. Two widget designs were just straight deleted. (graphs still intact) I would report as bug but, “list steps to reproduce” yeah right.

looks like old ue4 bug, If I remember correctly it sometimes happens after ‘replace with child’ is used or sth and reopening editor. would paste link but answerhub is down.