Weird... and self-inflicted to ~some extent, but still worth mentioning.
I have a tab group... I duplicate it in prefs several times in order to modify to make some variations of this group. Screenshots explain best what happens after initially double-clicking on one of the copies in order to edit it:
Here all is fine...
...I'm now going to dbl-click on the active tab in the right file display pointing to E:Comics in order to edit the path:
Once I've dbl-clicked on that tab to edit the path, I do so by simply overwriting the E drive with F:
...and a drop-down appears like the sort you get for path completion in other dialogs. I hadn't noticed it really before and must have clicked on it while trying to click the Ok button to finish my change. Clicking on it before Ok caused the path string to turn into F:\COMICS
And this is the result... I suppose the forward slash that got added in front of the F becomes ambiguous and Opus then resolves the nonsensical path to 'something' default-ish?
Weird... and may not be unique to v11, I'm just noticing it because of rebuilding my old config manually.