Well, how are you deleting the User records?
Other than that, is there anything in the log files about foreign key reference violations?
Can’t surmise much more without more source code.
Jason
I believe the reason it is not calling before_destroy on the dependent records is because it does a mass delete of all the subscriptions which is much much much faster than loading each of the records in order to call it's before_destroy hook.
I tihnk the workaround you came up with is the best compromise of architecture and performance.