Tested via mobile app on Android. I opened the app viewed my profile, tapped edit even, didn't save anything, tapped wallet, it's set to external wallet, I went through the workflow to add a NWC address, but did not save it, and backed out of settings, my Lightning address is unaffected.

I dunno man.

Did you say that you did create a NWC wallet?

Also are you on iOS or Android?