1.) Create 4 tracks
2.) Solo 2 of the tracks
3.) Shift select all 4 tracks
4.) With all 4 tracks selected, press ‘Solo’ key command to alternate solo’d tracks to be muted and vice versa.
5.) Now, with the same tracks, open their lanes, and try doing the alternating again.
Instead of alternating like they did in step 4, all tracks will become solo’d.
No problem at all here on Cubase 12.0.20 and Windows. I don’t know how you managed to get this “issue” but that must be a preference thing and not a real bug.