GE Add ons do not have radios inside them, they just communicate with their master via physical traveler wire.
Assuming the master is still working OK, then almost certainly when you went to paint the wiring Came a little loose at one of the connections. Just Turn off the power, open everything up, clean the connections if they are dusty, and re-tighten all the wires. That should do it, there really isn’t much that can go wrong with those devices.
If you painted the bare metal beneath the face plate it’s possible you eliminated one of the connection points, that metal is supposed to stay bare. But that’s not as common as just having a wire work a little loose.
Agree with @HalD. I’ve been using GE switches and outlets for over 5 years and I have never had an Aux fail me. In fact I have 4 installed since 2015 even though the master switch has been swapped out for a plus model.
Please double check your wiring because loose screws can cause fires