Illustrator/Dropbox (MAC/PC) incompatibility

Illustrator files created on a PC will sync to dropbox.com and back to a MAC.
Illustrator files created on a MAC will sync to dropbox.com but not back down to a PC.

I've already check the 14 steps or so for path length, invalid characters, purge index cache, update dropbox, restart machine, etc.

It appears to sync most files just fine. However I do notice that when I download (mentioned illustrator files) onto a PC, there's a subfolder (_MACOSX) file folder that has the same files but with a "._" appended to the front of each filename.

Adobe CC apparently is saving these files with an extra hidden file, that somehow is preventing dropbox from properly syncing it to a PC.

Someone at Adobe or Dropbox needs to get this situation fixed.

This guy seems to have the same problem I do!

https://linustechtips.com/main/topic/580215-dropbox-will-not-sync-illustrator-files-on-windows-10/​

How can I fix this?