If I'm understanding your question (due to my lack of tech understanding, not any fault of your communication), the NAS syncs to its cloud storage any time a file changes. According to Windows Explorer, the EXB file's time is updated every five minutes (and a few seconds) without any input from me.
I've had this setup for at least one year and haven't had this issue until about three or four months ago. That three or four months estimate is based on 29,000 (file versions on the cloud) X 5 minutes = ~145,000 = 94 days. I do not know exactly when the issue began.