Really? Tapping the Silent/DnD options in Settings does not help?
Also, maybe it’s the problem with pulseaudio stopping to work which could be unrelated to Situations?
BTW, switching Dnd/Silent mode on and off seems to work for me with Situations…
If this continues to cause problems, you can alternatively use systemd to do it for you:
nemo@PGXperiiia10:~/.config/systemd/user $ cat dnd-activate.service
[Unit]
Description=Do-not-Disturb mode toggle
[Service]
Type=oneshot
ExecStart=/usr/bin/dconf write '/lipstick/do_not_disturb' 'true'
nemo@PGXperiiia10:~/.config/systemd/user $ cat dnd-activate.timer
[Unit]
Description=Do-not-Disturb mode Activation
[Timer]
OnCalendar=Mon..Fri 23:59
OnCalendar=Sat,Sun 01:15
Persistent=true
[Install]
WantedBy=timers.target
nemo@PGXperiiia10:~/.config/systemd/user $ cat dnd-deactivate.service
[Unit]
Description=Do-not-Disturb mode toggle
[Service]
Type=oneshot
RemainAfterExit=no
ExecStart=/usr/bin/dconf write '/lipstick/do_not_disturb' 'false'
nemo@PGXperiiia10:~/.config/systemd/user $ cat dnd-deactivate.timer
[Unit]
Description=Do-not-Disturb mode Deactivation
[Timer]
OnCalendar=Mon..Fri 06:30
OnCalendar=Sat,Sun 08:30
Persistent=true
[Install]
WantedBy=timers.target
nemo@PGXperiiia10:~/.config/systemd/user $