Library Path: C:\Users\ajroy\OneDrive\Pictures\Lightroom\Lightroom Catalog-2-2-DESKTOP-94CC2MV-v13-3.lrcat   Actually, while you do have a copy of the catalog on OneDrive, and that library path indicates that. I do not think you are actually working from the copy on OneDrive, but from a copy on your C drive in your Users Folder. The presence of the word OneDrive in that library path indicates (I think) that the contents of that folder (in effect c:\Users\ajroy\Pictures\Lightroom\Lightroom Catalog-2-2-DESKTOP-94CC2MV-v13-3.lrcat) are being automatically synced to OneDrive.   Both actually working from a catalog on OneDrive, and working from a catalog on your hard drive but auto-synced to OneDrive are bad. LrC does not support working off the cloud, or a NAS, or any network share. As for an automatic sync to OneDrive, that is highly problematic.   If you automatically sync a LrC catalog to OneDrive, then every single edit you accomplish, every single mod, results in a communication across the Internet to your OneDrive. This gets very very busy. If you are having a bad Internet day, things can go downhill, in theory (I cannot prove), a catalog corruption can occur. At the very least LrC can slow down.   I would advise that you eventually create a folder on one of your hard drives, likely a root folder, with a name you like that is not associated with OneDrive, System folders and user system libraries (such as Users, Documents, Desktop, Music, Pictures, Videos). A name like MyPhotos, Lightroom, Rumpelstiltskin, GrumpOldFart (anything but Music, Pictures, Videos, and NOT under Users) and move your catalog to that location.   You could always backup to OneDrive, just try not to do that while trying to edit in LrC.   P.S. backing LrC catalogs and/or photos to OneDrive may or may not be efficient depending on how large a space you have at Microsoft.  ... View more

Are you referring to live tether? The Canon 5D is supported for tethered capture, but not for live view support.   This is shown in: https://helpx.adobe.com/lightroom-classic/kb/tethered-camera-support.html   note: in the above link, under Canon cameras supported, the 5D is not listed logically along with the EOS 5D Mark II, Mark III, and Mark IV, but further down the list for some reason only Adobe can state. ... View more

I have to build 4000 previews, this is insanly slow, I need to wait almost an hour to get them build. Actually, in my experience, just a few hundred can take an hour or two. That is why, when on a photo trip, say for example to a National Park, I copy my day's photos to my laptop first, then start my import (via ADD option) with minimal preview creation and go out to dinner, when I return, they will be ready for editing. Typically, this a 200 to 300 images. So 4000? Yep that can hurt.   If you are not using the Add method, consider using that as to spread your import process into separate steps that hopefully can be managed better. Overall time for the complete workflow may not be less, but more tolerable. This is an import workflow used by some Landscape Photographers. One advantage is to get photos copied (copy, not move) from the memory card to a hard drive ASAP. Then, using the Add instead of Copy option, and likely with minimal preview creation, minimal presets, the catalog can be populated, then the previews created later, perhaps as a batch, or more likely as you cull thru the images. ... View more