I’ve now tried the three following things:
1: As in the OP’s vague example I’ve soloed every track I have in my project and all tracks mute like they are supposed to. Nothing unpredictable.
2: I then wrote mute automation on one of my tracks (#1) which had dialog on it. The track mutes for about 3 seconds. When I solo other tracks this track with mute automation indeed “plays back” the automation, but audio isn’t playing out when the track umutes even though the mute light goes off.
So to clarify: Even though the actual mute button indicates mute is off, audio is NOT playing back.
3: I now routed tracks 1-3 to Group A, and 4-6 tracks to Group B. Soloing any track/group in any order resulted in the appropriate track/group soloing with it. I.e, soloing track #2 which went to Group A resulted in Group A soloing as well. Soloing Group B resulted in tracks 4-6 soloing as well.
It should be noted that soloing Group A resulted not only in tracks 1-3 being soloed as well, but that track 1 now executed its mute automation with “audible” results.
4: I took the routing from example 3 above and added an FX channel with a reverb on it. Track 1, which goes to Group A, now sends to this FX reverb.
Soloing the reverb FX channel also solos track 1 (but not Group A).
Soloing track 1 also solos BOTH Group A and the FX channel. Mute automation is active and “audible”.
Soloing Group A results in tracks 1-3 being soloed as well, but NOT FX reverb.
It should be noted here that if I solo track 1, which then leads to both group A and FX to follow (solo), the disarming of the solos depend on which solo you hit next:
Pushing the solo button on track 1 unsolos all three.
Pushing either Group A or FX unsolos ONLY that channel.
5: Now adding to the above I routed from track 4 to the same FX reverb. This results in exactly the same behavior as above, but with the following two notes:
Track 1 had mute automation on it, and when the track unmutes it sends neither to the outputs nor to the FX channel.
Soloing the FX reverb channel now soloes both track 1 and 4, as they both have sends going to the FX.
To me that seems to cover a lot of bases. If you guys want I can check some other combos.