I’ve just started using InSync for the first time to try this probably the best solution available.
But I have encountered an important problem on the first day:
If I delete a file locally, it’s also deleted remotely, BUT if I add or move a file (somewhere else in the local Drive directory) nothing happens 
So this file is not accessible either via web browser or another device.
Any ideas?
UPDATE:
After logging out and back in, the problem disappeared. InSync is now constantly on watch and instantly updating the remote with any such local modifications 