Well the change of cable seems to be the issue somehow. However if you want to try to updating the plugin you could follow these steps.
Use the UI to back up the existing plugin files first - always a good move, as plugins seem to come and go:
D_GC100.json
D_GC100.xml
I_GC100.xml
You should be able to "unhide" the existing three children (if they exist) with:
luup.attr_set("invisible", "0" ,<deviceID_IR_1>)
luup.attr_set("invisible", "0" ,<deviceID_IR_2>)
luup.attr_set("invisible", "0" ,<deviceID_IR_3>)
return true
in the Lua test window in the UI, where you have inserted the id of the three children above. If they don't exist that would seem to be an issue.
Turn off automatic updates for the GC100 plugin in the UI.
Then overwrite files with the four files from here - noting there is one extra file (L_GC100.lua) You can upload them using the UI upload. Make sure to uncheck the "Restart Luup after upload" then recheck it when upload the last file. After the luup engine restart and after a bit refresh your browser then: If the plugin update is successful you will see this variable: "UseGC100Codes" when the variables are listed in the UI.
Regardless it seems you may have some other problem if it all used to work and a cable change caused problems.
The GC100 code I modified works on Vera and openLuup. Good luck; not sure I can help much further.