Revert back to internal bluetooth controller doesn't work

When the Mac mini 2018 was released, I was experiencing Magic Mouse 2 issues (choppiness, etc), like many others actually, so I decided to get a bluetooth adapter (IOGear GBU521) and see if the problem would go away. It did...

I plugged in the new adapter, went into Bluetooth Explorer, under "HCI Controller Selector" selected my adapter "Broadcom Corp, Location ID XXXXXXX", made it ACTIVE and I was good to go. One thing though. When I would reboot, it would go back to the internal bluetooth controller so after reading about it, I used this Terminal code sudo nvram bluetoothHostControllerSwitchBehavior=always and all was good...

A year later and after moving my workstation around, I would like to go back to using the internal bluetooth controller but it seems I can't.

This is what I did... I unplugged the Adapter and the mouse and keyboard no longer show under the bluetooth devices panel, for me to Connect to. So I tried the following...

1- Unplugged all devices and hubs going to the Mac mini except for a wired mouse, keyboard and monitor so I can set things up.

2- I entered this code in Terminal sudo nvram bluetoothHostControllerSwitchBehavior (to go back to the default setting).

3- I trashed com.apple.bluetooth.plist & com.apple.bluetooth.xxxxxxxxxx (random numbers and letters)

4- Shift-Option to Debug (Reset the Bluetooth Module, Factory reset all connected Apple devices, Remove all devices) re-booted.

5- PRAM (Option-Command-P-R)

6- SMC (Unplug AC cord, 15 seconds, replug and wait 5 seconds) Reboot.

I'm not sure what I may be missing here but all that I've tried so far isn't working and I've tried it multiple times. Maybe there's a Kext file I need to delete but I'm not sure what to do. I know I can plug the Adapter back in again, and the mouse and keyboard will show up in the Bluetooth panel but I shouldn't have to anymore.

Any help or advice would be appreciated.

Thank you.