I've solved the issue.
When I updated from Launchbox 13.12 to 13.19 AND updated retroarch from within manage/emulators my retroarch games' controller (Xbox 360) no longer functioned. While I hadn't updated Launchbox in about a year... I hadn't updated retroarch for YEARS. For some reason, my Mayflash WiiMote interfered with retroarch's port 1. Just updating port 1 did not solve the problem.
The following steps did solve the issue:
DELETE retroarch.cfg file
Launch retroarch.exe
o settings / input / retropad binds
§ Change Port 1 Controls from WiiMote PC (1) to Xbox Series Controller
§ Using Xbox controller, Save controller Profile
§ Repeat for Port 2 (as I have 2 Xbox Controllers)
o settings / input / Hotkey
§ enable Hotkey should show ---
§ Quit (Controller Combo) = start & select
o Main menu / online updater
§ Update Installed Cores
o Main menu / configuration file
§ Save current configuration
