Also experiencing this on macOS 26 beta 2, Xcode 26.0 beta 2: SpeechAnalyzer: Input loop ending with error: Error Domain=SFSpeechErrorDomain Code=10 "Cannot use modules with unallocated locales [en_GB (fixed en_GB)]" It happens with both en-GB and en-US. Strangely, no such error is thrown with ja-JP. My first recording with that locale didn't get transcribed, but my second one did.

It looks like Core Audio would be appropriate for capturing audio from devices, but what if you want the audio that's output by an application/window? Is ScreenCaptureKit the only option for that case?

In my case, it was because I had the Comment Here Xcode Extension installed, which I'd set up to handle comments through Comment Here > Toggle Comments (Editor Menu for Source Code) instead of the usual Xcode action, Structure > Comment Selection (Editor Menu for Source Code). It appears it had lost permissions following an Xcode update. I granted it permissions again through System Settings > Privacy & Security > Others > Extensions > Xcode Source Editor: