Smart switch online but not operating or respond to config!

[Brawl]

I've had a smart (bathroom) switch for about a year, which worked fine to control a heater but now find that it's online but failing to switch the device on when necessary and the app won't let me adjust settings. I can switch it on and off remotely so it's clearly connected & the account works, just not 'active'. Has Tuya stopped supporting this product or blocked it in some fashion?

UPDATE - Fixed it! Turns that the 'Child Lock' on the app had been selected somehow! Subtle - no error or informational messages anywhere, just a padlock that appears on the switch itself ...