Have you tried rebooting after you changed the drive letters?
That probably means you have either created a system-wide hotkey on that key within Opus (Settings > Customize Toolbars > Keys), or you've floated the Operations toolbar (so the toolbar itself is a separate window, not connected to a lister or file display; that will make any hotkeys in the toolbar global).
Yes, I have tried rebooting every time. I just noticed what is probably an important thing. The drives show up under "Network Locations". They are still not visible in Explorer.
If you paste shell:::{289AF617-1CC3-42A6-926C-E6A863F0E3BA} into the path fields in both Opus and File Explorer, does either program list anything there that mentions the old or new drive letter?
Similarly, if you do the same with %APPDATA%\Microsoft\Windows\Network Shortcuts do you see anything about the drive in either program?
Are you running Opus elevated ("Run as Administrator")? It'll say "ADMINISTRATOR" in the titlebar if you are. That could explain things, as the admin context can have a different set of drive letters to the standard user.
Thanks for sending the log file! But it doesn't look like the This PC folder was opened/refreshed while the logging was happening?
Each time the This PC folder is loaded, it should cause Opus to look in the Network Shortcuts folder (among other places). If I filter on those events like this:
Did you open the This PC folder in Opus while the log was being made?
(The folder needs to be opened or refreshed after logging begins. If it's already open in a tab, just bringing the window or tab to the front may not cause anything to happen.)
That's the wrong type of log file. (Looks like either a summary of some kind, with counts of events per process but without any individual events, or something saved from a Task Manager type tool rather than Process Monitor.)
I am not as familiar with process monitor. I believe I captured what you want. I opened Explorer and opened Opus several times to display to phantom files. Hope this was a good capture.
It looks like there are mapped network drives under the old letters, but we need to work out why Opus is showing them and Explorer isn't. Once we know that, we should be able to filter them out in the same way.
We'll change Opus to ignore these, but if you expand that Network branch in regedit and delete the empty B, D, F and S keys there (only leaving the Z key which has something in it), then reboot, the unwanted drive letters should go away.
Since they are empty, they won't be doing anything and are safe to remove.
(Why something has created those empty keys in the registry, or failed to clean them up properly when removing them in the past, I am not sure.)