This might be the problem for other users but I already looked at the save hotNess attached. And you can see that with this save the main_quest is 90 and that 15 rehearsals have already been done. If you continue with the main quest you get the task to continue the rehearsals at main_quest=96. But if you're in the rehearsal room and talk to Michael the "Let's start rehearsal" dialogue option does not appear, because it only appears if you have less than 15 rehearsals. See:
And without the "Let's start rehearsal" dialogue option the section which sets main_quest=97 isn't called. So you're stuck.
The problem appeared because the same line in v0.90 (and older) have higher rehearsal values. The devs obviously reduced the values to reduce grinding. So you needed more rehearsals in previous versions which is the reason why hotNess have already done too many rehearsals (old save was transferred to v0.92.0). And that may be one part of the reason why the devs say old saves are not supported in v0.91/v0.92.0.
Code:
"{b}Начнем репетицию{/b}" if mesto == 72 and repa_today == 0 and hour >= 15 and (ruth_znak == 0 or ruth_znak >= 12) and ((main_quest > 50 and repa_all < 9 ) or (main_quest >= 77 and repa_all < 13 and main_quest < 80) or (main_quest >= 80 and len(song_all_) >= 6 and repa_all < 13) or (main_quest >= 96 and repa_all < 15) or (main_quest > 117 and main_quest < 122) or main_quest == 131 or main_quest == 136):
The problem appeared because the same line in v0.90 (and older) have higher rehearsal values. The devs obviously reduced the values to reduce grinding. So you needed more rehearsals in previous versions which is the reason why hotNess have already done too many rehearsals (old save was transferred to v0.92.0). And that may be one part of the reason why the devs say old saves are not supported in v0.91/v0.92.0.