This has been an absolute disaster. I performed the macOS upgrade and then was on the road, we work entirely off of OneDrive so that meant I had ZERO of my files with me on my computer. Further, we setup OneDrive to be on external hard drives and now that it pulls everything into the root directory of the smaller local drive it basically fills up our hard drives. We've had to wipe computers clean and start with a fresh OS install in an attempt to clean up the mess, but then when we setup OneDrive and create the base directly on the external hard drive all we get is a link on the external drive and all the files back into the local OS partition. Whoever came up with an architecture that doesn't let you separate your data from the OS should be fired, and this basically means we can't use external hard drives anymore for OneDrive partitions (I know there is some work under the hood to make that still kind of happen, but my local hard drive is still filling up and creating massive GBs of purgeable data...horribly inefficient and so dangerous to fill up the drive that contains the OS). It is IT 101 to have the OS on separate partition from the data files.
I've spent almost my whole week dealing with this disaster and nothing else. I reached out to MS support and they were completely clueless and closed the ticket as "resolved" because the support person was going home for the night and couldn't even grasp what I was asking. This is all so unfortunate as I've built my company around Office 365 and OneDrive but given how horribly this was handled am now looking at alternatives. If you can fix this before I switch I will reconsider, but I sincerely doubt anything will get fixed.
People work off external hard drives and they often work without internet connections. Whoever on the OneDrive team didn't realize this and made the awful decisions around this architecture and to make all files "on demand" (without even telling us) should not be in charge of this product. Everyone already had everything setup in OneDrive via the "Choose Folders" options as to which folders we wanted online vs. offline, why in the world do I now have to redo all that configuration (and redownload everything), on top of all the other issues (spotlight, trash, and external drives)? Just unbelievable how horribly this was implemented and being managed...I don't care if Apple forced the change via their APIs or not.