Personally, I've had endless sync issues with Google drive. It doesn't seem to have any sort of 'retry' feature if it can't sync a file other than restarting the service.
If you have your own server, I'd recommend BTSync. Sync any folder on your computer easily, without having to move them into a specific folder. You could probably set something up to also sync everything to Google Drive with a script, for redundancy.
Could be a weird bug. I have a lot of files in my drive and don't have any issues so far. My drive is set up to sync on windows and mac. Also use it on my android and web.
