I´ve indeed noticed that too, but I am not sure how to fix that.
I feel it has to do with the snapshot for the group and then the restore as well as the unjoin…I´ve been thinking to try by separating it and creating a specific script to test for when all sonos devices option is chosen. In that script I would then separately call a snapshot and restore for all individually, so just some extra steps.
Lack of time at this moment is what prevented me from testing that…so let me know if you get to that.