Nintendo Switch controller issue

My kids have been playing minecraft on the switch for months, together. But recently, and for no apparet reasons, when they try to play together, they get prompted with the following error message - While in local wireless play, no more than two pro controllers or one joy-con controller pair can be used. Please turn off all extra controllers

Disconnecting controllers and restarting doesn't resolve the issue. I am connected to a Local network, not Online. I