I'm editing some New Quizzes that were recently migrated from Classic Quizzes and I noticed this bug happening at random (regularly enough that it's causing me problems)—if I try to "delete" a blank in Fill in the Blanks (by clicking the x, which normally turns the blank back into regular text), every so often there will be one blank that cannot be deleted no matter how hard I try. I click it and it makes the whole page glitch out, turn blank, and revert to my last saved changes when I refresh. It seems totally random, but once it starts, that blank can't be rid of the glitch.
I've had the blank screen thing happen for other reasons too, but this one is most prominent—80% of the blanks behave like they should, so I don't think the issue is on my end, but I'm editing hundreds of questions, so the glitchy 20% adds up. Has anyone else had this happen?