I used Fn keyboard shortcut to disable bluetooth in my notebook and all drives except C and D disappeared. But they are still grouped in "unspecified" category (despite if I change to details view it says it's filesystem is NTFS).
On my side, I've tried more things, including switching Windows to Polish (in case there was something to do with the Type strings), but still no luck reproducing it.
In case it's to do with the folder format, could you zip up and attach this config file:
/dopusdata/Formats/shell.off
(There shouldn't be anything private in there, but you can look in a text editor to double-check. At least for me, it's just a list of columns and other details about how the Computer and MTP folders are displayed.)
If you turn on Show empty disk drives for the computer folder (the checkbox near the middle of the last screenshot of the first post), does that make a difference to what happens?
The previous beta had some changes to how empty drives are detected/updated, so they might be related, I guess.
If I turn on showing empty disk drives, DVD drive appears and all DVD, C and D are grouped in "unspecified" group.
Grouping by type works ok. C and D are classified as hard disk drives and DVD as drive with removable storage.
I will use this as a workaround for now.