Hi everyone, new here and so appreciative of the work that's gone into allowing us to keep using our older macs at the highest level of functionality. However I have an issue that I couldn't find discussed in this thread or on the forum generally, hoping someone can shed some light on it. Some background:
I'm on a 2010 i7 MBP with the C9560 capacitor graphics issue, and have been using Julian Poivedin's software fix with stable results on 10.13 for a while. I've been backing up my internal SSD to an external HDD with Time Machine (a mistake to not simply have cloned, in retrospect). Curiosity getting the better of me, I recently upgraded to Mojave using the updater patches and a partition of the HDD as a bootable installer. After a few hiccups that I attributed to triggering the graphics problem and causing panics during installation, I was able to successfully update to Mojave (not a clean install) and used it for a week or two uneventfully.
Where I fear I really pushed the envelope was a foolhardy attempt to bump to Catalina after such smooth sailing (thanks to many of you here) with Mojave. I performed a single Time Machine backup and went about it, again with success using the patcher. However the cooling fans didn't love the constant graphics acceleration of this and that, and I found the software graphics fix to be inconsistent, so I decided to revert.
Long story long, I have run into the same issue upon restoring my machine from both Mojave and High Sierra backups, which is that my entire Photos library is nonexistent upon completing the restore each time. This is a 50+ GB set of files that has seemingly vanished.
I did open photos during my time running Mojave, prompting it to "update" or optimize, and my main guess as to the issue is regarding the file system structure and issues between backing up my internal APFS drive to an HDD (formatted as Mac OS Extended) and then attempting to restore. From all appearances when going through the restoration process, the backups intend to fully replace the photos library I had ~30 GB free space on my machine prior to all of this. However upon completion I'm left with closer to 100 GB free space and no photos library. Inspecting the backup folders on the HDD each of them now has no trace of a photos.library whatsoever, which needless to say is very worrying. All the other files including files within pictures remain unscathed, even my monstrous itunes library makes the jump without apparent issue.
Apologies for the long comment, searching for any leads to hopefully still recover decades of photos, as I foolishly played around expecting my backup to perform well and instead Time Machine has not had my back.