Thanks Marko. Here's a full repro case:
1. Fully uninstall MC, including registry entries and libraries
2. Install 12.0.363
3. Import a folder(s) with a total of more than 50 tracks into the library
4. Create a new playlist
5. Click on Audio, and drag+drop the first 30 tracks from the filelist on the right onto the playlist in the tree on the left
6. Drag and drop an additional track into the playlist
EXPECTED: last track is added at the end, as seq=31
RESULT: last track is added in the middle, as seq=13 (the actual wrong position is random). This is reflected in both the action window (which opened by default when I created the new playlist), as well as when I click on the playlist to see its contents on the right
Right-clicking on the playlist gives me "Edit Playlist in Action Window", but I don't see the two options you mentioned - all it says is "Drag and drop files here". Which makes me wonder - are you using the same version of MC as I do?
And yes, I can drop a track either into the middle of the action window, or on the text "Drag and drop files here" (which adds the tracks to the end), but I need access to all my playlist groups and playlists while I DJ, so I can't give up the screen estate by having the playlist open in the action window. Right-clicking on a track and choosing Send To->Playlist->PlayListA works too, and adds the track to the end, but that's too cumbersome for repeated use as I build DJ playlists on the fly.
Instead, I want to drop a track from the filelist on the right side (either a view scheme file list or another playlist), and drop it on a playlist in the tree, and I need the track to be added to the end, not randomly in the middle. As I said, this was how MC worked at least until 12.0.158, and the behavior I see now is consistently different on two machines for 12.0.363.
Thanks again for looking at this.