Can't add Meross devices

I’ve been going through and tidying up all my accounts as Google Home had started to act funny and wouldn’t control some devices. I have a Meross wall plug (UK mss310) which works fine through the Meross and has up to date firmware but when I try and add my Meross account to SmartThings it goes to processing then says “We’re having trouble connecing. Check your network connection and try again”. After I OK out of that and go to settings, connected services I can see Meross in there but none of the devices are in my home. I delete and try again, same issue!