White blocks blocking the UI, not findable on the design page

Questions
1

In the last couple of days, many of my app pages have started showing white blocks that hide the UI. I look on the design page, check every element, but there’s no group or other element on the page where the block is. I’ve built pages from scratch, and while I’m building it’s cool, but when I go to the page in the app, about a fifth of the page is hidden. Anyone have any ideas I can try to make the block go away? Thanks - dk