MBP won't recognize airport utility in Catalina, but will in Mojave

I had what I thought was a bad airport card, but when I replaced it I still had the same issue—in system report it said airport not installed.

When I booted from an external hard drive however voila! Wifi working strong. Booted right back from internal (Catalina) and no dice. After some research I tried wiping the computer and installing Mojave and once again, the wifi works.

Does anyone know how to rectify this? I need Catalina for a few programs, otherwise I would live with Mojave.

Last resort is to get a usb wifi, but I feel like there must be a way with the internal card!

Thanks in advance if anyone has an idea here.