@eson, did you ever reboot the phone when the night ambience was active, and switched to the day ambience only after reboot? If not, please could you test it? I mean:
- enable the ambience which has SMS and email sounds set to “No sound”
- reboot the phone
- after reboot switch to your day ambience which has SMS and email sounds enabled
- now please check in Settings / Sounds and alerts if all sounds were correctly changed.
In my case, ringtone, SMS, email and alarm clock sounds remain unchanged (i.e. still “No sound” of the former ambience). And if I go to that second ambience settings, I can see only sounds for chat and calendar listed, all the remaining options (SMS, email, ringtone, alarm clock) are gone. It is 100% reproducible, 10/10. On both XA2 Ultra and 10 III. And it looks that I am not the only one as there is a bug report describing the same issue with alarm sound setting disappearing from ambience setting: Make alarm sound setting in Ambience persistent