Photos crashing when I try to upload photos from iPhone 12 mini

Hi, all - I'm using a 2019 13-inch MacBook Pro. My software is up-to-date, with Big Sur 11.3.1. I've previously had no problem uploading photos to Photos from my iPhone, which is a 12 mini running iOS 14.5.1, which is also up-to-date as of this writing. However, today, whenever, I click on "Devices" in Photos, I briefly get the "Preparing to import from iPhone" message before Photos crashes. Sometimes I make it to the "Please unlock your iPhone" screen, but it also always crashes after that. I've ejected the phone and shut down the computer, but I still had the same problem when I restarted it. Help?