DAX RX audio not exported – “DAX Audio RX 1: Not plugged in” on Windows 11 (8600M)

I’m looking for guidance on a DAX RX audio failure that appears to be radio-side or firmware-side, not PC configuration.

System: Radio: FLEX-8600M
SmartSDR for Windows: 4.1.3 → upgraded to 4.1.5 (no change)
Windows: Windows 11
Digital software: WSJT-X / JTDX (both tested)

Symptoms
Panadapter works normally (RF and DSP OK)
TX and Mic DAX paths work (Mic stream goes blue)
DAX RX audio is never exported

In Windows Sound → Recording:
DAX Audio RX 1 = “Not plugged in”

Sound Recorder on “DAX Audio RX 1” records flat line (zero samples)

In DAX Control Panel:
RX Stream 1 never turns blue
Occurs before any digital software is started
Occurs regardless of CAT method (serial or TCP)
Occurs with multiple Global Profiles (including default)
Cold boots of PC and radio do not change behavior

Reinstalling / repairing DAX drivers fixed DAX startup errors, but RX audio still not produced

Things already ruled out
Windows audio device selection (multiple valid playback devices)
Windows microphone privacy (desktop apps allowed)
WSJT-X / JTDX audio settings (correct)
DAX driver installation (now loads cleanly)
Slice DAX assignment (DAX = 1 confirmed)
RX AF gain / mute
“Mute local audio when remote” enabled or disabled (no effect)

Key observation
Windows reports “Not plugged in” for DAX Audio RX 1, which indicates no producer attached.
This suggests the radio is not instantiating the RX audio export graph, even though DSP and panadapter work.

Question
Has anyone seen this condition where RX audio is not exported to DAX at all, resulting in “Not plugged in” on RX 1?
Is this a known firmware issue on the 8600M?
Is a radio factory reset the recommended next step?
Is there any other radio-side recovery procedure for the RX audio graph?

I’m trying to avoid random reconfiguration and focus on the correct radio-level fix.

Thanks for any insight.