I'm very interested in this too. If not using Instruments, is there any other way to inspect CPU Caches, branch predictions, etc on Apple Silicon for performance-related work?

Is there any known workaround in place? I'm facing the exact same problem on Sonoma 14.2.1 with Xcode 15.1 (15C65) when attempting to record signposts from C++, which definitely used to work before. I confirm that even os_signpost_enabled returns true when logging under the Logging template, but nothing is actually recorded. Neither events nor intervals.