Recently I experience a lot of folders from Onedrive (within Odrive) showing up also on Amazon drive (really syncing there and taking up space. After several tests I suspected that the “culprit” was Pathfinder (that I used for many years and gave me no trouble until recently). I don’t know for sure that the trouble started with High Sierra but I strongly suspect it did. I uninstalled Pathfinder and everything went quiet. If you have data confirming or rejecting my supposition WRT Pathfinder please speak-up.
We don’t test against Pathfinder, so unfortunately I can’t say whether an incompatibility like this exists, or how it would manifest. We use a Finder extension and it is possible that Pathfinder has some issues with that, to some degree. The fact that files are being copied to new locations is definitely odd and unexpected, though.
Thanks for the report!