So that's another/different problem?
Kodi is shutting down before a timer is getting set?
Yes, according to your log kodi seems to be hanging on shutdown while/after disconnecting VNSI and is killed finally. This is behaviour by design of the LibreELEC kodi SIGTERM implementation.
Kodi will even fail when going further and trying to set the timer because it cannot read its own settings any more.
Quote
Does setting a timestamp (using setwakeup.sh date '+%s' -d '+ 10 minutes') works on your system?
I am getting an error but there is always a timer 5 minutes ahead.
So could you try with 10 minutes pls?
Busybox's "date" does not accept parameters like "+ 10 minutes". You have to use something like
setwakeup.sh $(($(date +%s)+600))