I'm using the latest cloud-based version of LR and Photoshop. I'll use the context menu on a NEF in LR to send it to Photoshop, perform some edits, and then Save and Close to return the TIFF to LR. Back in LR, I'll do a few other simple edits; for example, a few different crops. So far so good. This process has worked for as long as I've been using the new cloud LR.
However, lately, when I go back to LR and check on those TIFFs, they no longer show up in the LR catalog. They are visible in the Finder beside the original NEFs. I have to jump through some hoops to reopen those TIFFs in LR. More importantly, the edits to the TIFFs are completely gone.
This has lost a good deal of work before I noticed the problem. If I look back historically in my LR catalog, I can find several TIFFs where this process worked properly and the TIFFs and the LR edits on them still exist. What is quite bizarre about this is how the process works on the original round trip. The TIFFs and the edited versions seem to be sitting there quite happily. It's only when I move on to other work and come back to that album that the damage is apparent.
I'm running MacOS Catalina 10.5.4 on a MacBook Pro. LR and Photoshop are the latest versions per my Creative Cloud drop-down. The NEFs are from a Nikon Z7, so they are fairly large. The Activity monitor doesn't report anything significant on CPU, memory, disk, or network resources. All seem to be within bounds. I've also run Disk Utility and CleanMyMac on my machine and found zero problems.
As a potentially related issue, I sometimes have clients come in and mark their favorite images from a shoot with 5-star ratings. It seems that several of these rating edits are also gone.