Unlock With Apple Watch Not Working In Catalina

[Allistah]

I have a mid-2011 27" iMac. The highest OS it supports is High Sierra. I've installed a K4100M video card and an upgraded BT module (BCM943602CDP). Everything works great in Mojave. But in Catalina, I can't get AWatch System unlock to work at all. I saw that some people disable serial ports and some people put in older graphics cards which solve the problem but I don't really have that option.

Anyone have any idea what I could try on this iMac to get system unlock to work?

 

[daredevll]

Hi. I come here to report I have Catalina 10.15.5 and I made Apple Watch Unlock work with FENVI T919.
I had in my Gigabyte Z390 M Gaming BIOS F9g ... Apple Watch Unlock was not working... I even tried Reseting Keychain on Apple System Utilities and it didn´t solve. I downgraded BIOS to F7 which has an option unavailable in the latest BIOS. This option is:

1. Peripherals:
   1. Super IO: disable Serial Port

After the downgrade and disabling Serial Port it is working now. Maybe it was just the BIOS downgrade that worked and Serial Port Disable has no interference... But I read somewhere a guy saying he also solved Apple Watch Unlock doing the downgrade and disabling Serial Port.

Also, I have IGPU Disabled and I´m using Gigabyte RX5700XT GPU.

It´s working now... Let´s see if it works for long time or just few days. If it fails again I will report here.

My config is quite different but just posting for search purposes to confirm this method worked for me! I've been struggling with this issue for a while and found it hard to find people with similar hardware and this isuue. Mobo - AsRock ab350m Pro4, Ryzen 5 1600, Sapphire RX 580 8GB. Disabling the Super IO > Serial Prot fixed it immediately.

Thanks dude!