I have exactly the same issue with Telegram.
Test notification works (so no token error), but real notifications (from backup) fails with error 400 on log.
Maybe as I have read before, not supported characters or too long message body, but I don't know how to correct.
Test notification works (so no token error), but real notifications (from backup) fails with error 400 on log.
Maybe as I have read before, not supported characters or too long message body, but I don't know how to correct.