I've done this dozens of times in a bunch of videos. Now it doesn't work and I don't know why.
When you use the FX Crop, Zoom, or Pan&Zoom/KenBurns there should be a preview window that has draggable borders to frame what you are cropping or zooming. (Looks like dashed lines with small square boxes at the corners and edges.). That border isn't there anymore. I did an update to the Mac OS last week so maybe that changed something?
Running VP 11.70 on OS X 10.15. Has anybody else seen this or have a solution?