I like the idea of notifying the user when the sync algorithm fails to version a file correctly and needs the user to perform further actions. The problem is that if you have 100+ files in conflict, then you'll get 100+ notification popups on windows 10; in this case the user, out of frustration, would just close the client and forget about all the conflicting files, defeating the purpose of having a conflict resolution system in the first place.
I'd say you guys should implement a notification system similar to the "Show errors when syncing files", that would hint the user that something went wrong with only one notification and let them resolve it in a per-file basis (stick with the local one or download the one on the server) without generating a ton of duplicate files.
Just talking from experience using this software. Thanks for reading.