Import problem. Cannot import anything

Final Cut refuses to import media from SD cards or anywhere else. This is a brand new issue that never happened before. And I've been using 10.4 and high sierra for a week or two before this happened. FCPX sees the media on my cards and lets me click import, but the clips just hang there, and don't import. The media shows up in my browser. No camera icon. Just an empty circle on the corner of the clips (that would usually fill up as the media is ingested). Also, if I look at background tasks, the media makes no progress importing there either. This is also true with files I try to bring in directly from my hard drive. Never saw anything like it. Just refusing to import. FCPX also crashes after I remove the SD card.

Yes, you have to quit FCPX to unmount a camera card. Have you tried trashing preferences and render files yet?

I've trashed the preferences. No change. Then I trashed every render file from all libraries. No change. The only way I can get media into FCPX at this point is to drag the files from the SD card (or elsewhere) into the browser. For AVCHD files, this means unpacking them manually first. BUT, I've just discovered that the sound is not coming along with the unpacked .MTS files. And now, larger clips won't simply drag over. They stall with the attached screen shot.

But even under these circumstances FCPX won't let me eject the SD card, though it is clearly not referencing it.