InDesign is messing up the preview

This happens to me every now and then: InDesign completely messes up the preview on my screen. If I zoom in or out, it usually disappears.

At first, I blamed it on my old computer, where the graphics card was probably failing, but the same problem persists on my new Mac Mini.

It doesn't seem to happen at all; it's completely random.

This issue is still not fixed with the latest update (21.0.1), and it's even worse.

If I move an object with a drop shadow, InDesign "moves" the entire shadow. Zooming in and out doesn't help; I have to completely close and reopen the document for it to work as it should.