Sounds like your ST server account was having issues, the fact that it took a couple of tries to save the settings is the prime indicator that it’s a server error. Once data is saved it’s all in the cloud and the app does not modify it, that seems to indicate data corruption on your account (not the first time on SmartThings, it’s happened before).
Another user also posted another thread about some random ST server errors with their SmartApp. Keep on eye on it. If the data continues to have issues you may want to contact ST support investigate why your account has data consistency issues.