Im having this exact same issue under Godot 4.2.2 and 4.3. I can record but the data is all zeros that come out. If I do AudioServer.get_bus_peak_volume_left_db on the recording bus he volume does go up and down so it is getting the input from the mic. If I dump the data I can I get
Format: 16-bit uncompressed
Mix rate: 48000 Hz
Stereo: Yes
Muted: No
Record enabled: Yes
Bypassing effects: No
Size: 561152 bytes
and the size varies by recording length. It just looks like somewhere along the way the data gets set to all zeros. Its the same when I look at it in the debugger or if I save the wav data to disk using recording.save_to_wav(save_path)
Anyone have any thoughts?