The syncing done by these services are NOT instantaneous, and that is why your DB could be screwed up -- the updates made to a table may not be actually sent (synced) to the DB at OneDrive until after several seconds, or minutes, or god knows how long.  And you can test this to see for yourself.  Turn on "autosave" in Excel or Word in the top left corner and start typing continuously for seconds or minutes, and you'll notice it doesn't autosave while you are typing!  It only autosaves several seconds after you stop typing or other activities.  This is the reason your files may not "sync" in a LONG time.  And that is detrimental to a database file.  Note that Access doesn't have an autosave button, and may not even have such a feature.  So you are completely in the dark as to when Access decides to sync or feels like syncing.

Even the word "sync" is confusing here.  When you open a file on OneDrive, you are looking *directly* at what is on the server side.  Yet, when you make changes to it, you don't directly change the data on the server.  You have to "wait" for it to "sync."  That could mean that you are merely looking at a *copy* of your file on the server, not the actually file.  If OneDrive does the same thing to an Access DB, I don't even want to know what is happening.  When you use a back end DB, you have to use the real thing, not a "copy" of the real thing.

Yeah... I did a test with Google Drive's offline sync. I edited some records in a DB on PC1, opened the database at the same time on PC1, those records didn't show up (of course). Closed em both down. Waited a few minutes for the sync. Opened it on both PCs again. Now the updates showed up on PC2. Made some changes on BOTH databases... and it was a toss up which one "won" the sync. Completely unreliable for database use.

I was using OneDrive to "sync" for use across multiple computers, even setting a standard mapped drive, and in due time, the DB that contained the core tables would inevitably get corrupted, with different network connections and speeds, along with random down times, or delays on their OneDrive SharePoint servers.

After setting up my own home server back in early June, 2023, after getting the proper access and dedicated IP from my ISP, I set up my own MySQL server for my back-end, and now typically as-needed, remote into my home computer running Windows 10 to do any work, especially as Office 365 was dropped from support of Windows 8.x, as it's no longer supported by Microsoft as well.

Granted, I'm still using the mapped drive on my home computer, yet it's only 1 point of entry / exit from the MS SharePoint, versus opening up on 2+ computers at different times, wondering when it would catch up in the updating process through those servers. And so far, so good, especially with using a MySQL server for those back-ends.