Looks like it now works correctly in both directions, using the "My files" app. Again, not certain what changed. Could be either on the Windows or phone side.

The 512MB file size limitation makes this significantly less useful than it should be. It is almost completely useless for video files.

I don't see any reason for it. My guess is that files are going back and forth through the cloud, rather than directly from phone to PC. It shouldn't have to be that way. My PC is on 10gig ethernet. My phone is on Wifi6. A transfer speed of 800 Mbps between the two is achievable. I have 4K video files that are >8GB on my SD card.

I'm still forced to use the USB-C connector, and put wear on it, in order to transfer files. Microsoft software still has a very long way to go to catch up to what the hardware can do. Very frustrating.