This worked in 12.0.363. In 12.0.365, the following happens:
1. Choose Run Auto-Import Now from Tools menu, same options as before.
2. Action Window shows that MC is analyzing the library, but before it's done, MC crashes without adding tracks.
3. I removed all auto import folders and re-added them, then ran Auto-Import again a few times which seemed to work.
4. I then added a few more tracks to some folders, ran Auto-Import again and MC crashed again, this time after it added tracks. The summary dialog never came up and the Recently Imported Playlist is empty.
Looks like a related change in 12.0.365 broke something.