Same here, it doesn't even work with the Safari Technology Preview. It's all broken, this sucks!!!!!!

I'm experiencing the same thing, just updated to Big Sur 11.4 and using iOS 14.5 device. It doesn't even work with iOS 13. It's all broken, this is crap. One week and no response, developing for iOS devices is a nuisance now.

It is staggering the lack of interest in fixing this issue for the Xcode simulators from Apple. Some users say it's working fine for real devices but not everyone that has a Mac has an iPhone (it'd be like buying another Mac ffs) and we rely on the simulator. I can't believe that something that should be so simple is not definitely within Apple's priorities to fix. Are they losing interest in supporting their Apple ID login then? Because if that's so, that'd be a better response for my clients to digest than having them annoy me everyday for something that's not even under my control. No wonder why Android is still leading the mobile market.