Scott,
No, I haven't any ideas about this fault. The comments below are just my suggestions about doing the steps that have been suggested in previous posts in this thread.
The steps suggested in this thread worry me to varying extends. You have not yet made a system image of your C:\ drive so anything drastic might force you to do a full reinstallation if it goes wrong.
I think it would not be a waste of time to run ChkDsk on your external HDD. In File explorer, right-click on your external HDD, select Properties, select the Tools tab, click on Check, [you will get an Admin challenge], then a confirmation dialog appears

but note that it is offering to scan & repair. I am nervous about suggesting this step because you would never know if anything had been changed that invalidated the system image you already have on it [unless you tried to restore from it and it failed
to work]. You will at least know one way or the other because the scan results are displayed when it finishes -

If the scan results show that anything was repaired then I think you will just have to make a new image for your Desktop.
It might not be a waste of time running ChkDsk on your internal HDD but I am sceptical about this step as I cannot see the connection between your HDD structure & the fault you are experiencing. In File explorer, right-click on your external HDD, select
Properties, select the Tools tab, click on Check, [you will get an Admin challenge], then a slightly different confirmation dialog appears

and note that it is offering to scan but then to check back with you before doing any repairs. I hope you do not find any faults but, if you do, you will have to decide whether or not to try letting ChkDsk fix them. You will have no idea if all your files
are intact afterwards [OS & application files and your own files on that same HDD]. Personally, I would make a full backup of all my own files onto an external HDD before doing any repairs. I would also do a system image as well but you are not really in
a position to do so.
Perhaps you'd like to try these steps & post back with your results.
Denis