iMac 17,1 - USB bluetooth dongle not working in Monterey

Give this a try:  Reset NVRAM or PRAM on your Mac - Apple Support (for Intel Macs) and the test both the internal BT and the USB dongle.

If still not working boot into Safe Mode according to How to use safe mode on your Mac, reboot normally and test again.

NOTE: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

Hi, I have about the same problem after upgrading from Big Sur to Monterey 12.2 and later on one of my Mac mini (2018i7)

The system report shows Address: NULL / State: Off / Chipset: BCM_4350C2 / Discoverable: Off / Firmware Version: v0 c0

I have tried al kind of solutions from the community without any succes. Also using an external Hideez USB dongle and other didn't work. It is clear that macOS Monterey has bricked my bluetooth chipset. And searching through the community and other sources this is a single case... The Apple hardware diagnostic test tells no hardware problems.

Question #1 Does system report shows the same results? Question #2 Have you found a working solution?

Question #3 Is Apple aware of these bluetooth Chipset BCM_4350C2 problems?

Same problem with 12.4 update. The Hiddez that was working now isn't recognised and the bluetooth in the systems report shows and Bluetooth is switched off and does not respond to any attempt to switch on. Here is the full system report which is the same as was shown in the question above.

  Address: NULL

  State: Off

  Chipset: BCM_4350C2

  Discoverable: Off

  Firmware Version: v0 c0

  Product ID: 0x0001

  Supported Devices: 0x382039 < HFP AVRCP A2DP HID Braille AACP GATT Serial >

  Transport: UART

  Vendor ID: 0x004C (Apple)

Same problem here with a Mac mini 2018 and Montery 12.2, 12.3 and 12.4 with the BCM_4350C2 chipset without any solution. Bluetooth worked fine with Big Sur! The only thing I've to try is a fresh downgrade to Mojave and see what happens with the bluetooth firmware. Other Mac mini 2018's with the BCM_4364B0 don't have any problem. Chatting with Apple Support gave no solution except that my device is out of warranty...

Here too the same problem. At first my entire Bluetooth option disappeared from the system preferences. Duddenly it was back. Bluetooth is recognized, but it is "off" and no way to turn it on.

The internal Bluetooth controller gives the following reading:

  Bluetooth Controller:

  Address: NULL

  State: Off

  Chipset: BCM_4350C2

  Discoverable: Off

  Firmware Version: v0 c0

  Product ID: 0x0001

  Supported Devices: 0x382039 < HFP AVRCP A2DP HID Braille AACP GATT Serial >

  Transport: UART

  Vendor ID: 0x004C (Apple)

So I connected a dongle. That one is recognized too:

  Product ID: 0x0001

  Vendor ID: 0x0a12  (Cambridge Silicon Radio Ltd.)

  Version: 88.91

  Speed: Up to 12 Mb/s

  Location ID: 0x14400000 / 5

  Current Available (mA): 500

  Current Required (mA): 0

  Extra Operating Current (mA): 0

However, there is no way to connect to the dongle, it works on a Mac with a working Bluetooth module though.

This article gives instructions which may help.

https://apple.stackexchange.com/questions/94402/force-os-x-to-use-bluetooth-dongle-instead-of-built-in-controller

I have exactly the same problem too, and after various unsuccessful attempts at solutions it is clear the OS is at fault. Apple please fix this.