I ran xcrun simctl list runtimes which includes: iOS 16.4 (16.4 - 20E247) - com.apple.CoreSimulator.SimRuntime.iOS-16-4 (unavailable, The iOS 16.4 simulator runtime is not supported on hosts after macOS 26.99.99.) So I guess that's that :/ Guess I'll have to try to get a Tahoe VM going if I can find the disk space.

... also handy for force-quitting apps in the simulator with a swipe up gesture in multitasking. device hub is missing so much 😭

I'm experiencing the same thing! So it's not just me. The strange thing is that for me, Xcode shows iOS 16 Simulators in the destination dropdown, but they don't appear in Device Hub. Which means I can build and run on an iOS 16 simulator, and Xcode shows that it has launched and is running, but there's no visible Simulator for it! I can't debug and run on a physical iOS 16 device at all, though, since physical iOS 16 devices do not appear as a run destinations in Xcode (nor in Device Hub) :(

follow-up: i have discovered that just switching to a different network, and then back, works around the issue for me. i don't even have to switch the other device and pair while on the other network. does anyone know if there's a way to do this network "reset" without actually switching between wi-fi networks? turning wi-fi on and off doesn't actually help—only connecting to a different network and back again.

if you are using a file that you know should work, it might be the web server not serving up usdz files correctly (with the right mime-type)? is it possible to share the URL to the webpage?

holy carp, juyoungk23's solution (switching to a different network, pairing, then switching back) is the only thing that works for me. thanks for suggesting that. please apple, fix xcode.

i am so tired of having to reboot my vision pro AND my macbook almost DAILY just to get xcode and the AVP to talk to each other again and again and again.

i followed @instantinteractive's suggestion but slightly differently: deleted /Library/Developer/PrivateFrameworks installed Xcode.app/Contents/Resources/Packages/XcodeSystemResources.pkg on my system at least, XcodeSystemResources.pkg creates the /Library/Developer/PrivateFrameworks folder. anyway that fixed "Toggle Appearance" in the Simulator for me! thanks for the tip!