Registering a channel using ServerLoginNetworking.registerReceiver does not work. The vanilla response of kicking the client when the server receives the client's query response packet is triggered instead of LoginQueryResponseHandler.receive.

The global counterpart ServerLoginNetworking.registerGlobalReceiver works fine.

I've made a demo mod here: https://github.com/DiffuseHyperion/TestingLoginQuery. Attempting to join the modded server should see you getting kicked with the message "Unexpected custom data from client", instead of being able to join the server normally.