Hi
I have exacty same issue , Changed Chime greeting over christmas .Now when changing it back it times out and gives some kind of error message after few minutes .
1 re-installed the App , made no difference.
2 removed device and re added it
3 totally reset the chime (by pressing the reset button 30seconds)
4 Removed and readded the wifi settings etc .
5 In the end I phoned support and they talked me through reseting the Chime again, it updated software ,but problem still exists .Support advised me to wait 15 to 20 mins and retry .
I notice the Chime has reverted now to ‘default’ tone , but still wont allow me to change it to anything else .It still works when the bell is pushed etc just slightly annoying .