WDM Question (locks out MME access?)

I use Adobe Audition in MME mode from the RealtekHD chip for quick edits which is quick and easy as long as SONAR is in ASIO mode. Recently I went back to check SONAR for playback on that chip and it is perfectly fine as long as SONAR is in WDM mode, 2msec buffer, and set to 16-bit (is actually locked here).
 
I just found out that WDM mode in SONAR locks out Audition being able to access the chip. I did a quick check of things:

1. Sharing/Not-sharing drivers in SONAR has no effect.
2. Set Windows default for that chip to 16-bit (normally at 24-bit) to match SONAR to no effect. SONAR actually says the WDM chip driver recommends 16-bit for WDM and locks it there in SONAR preferences.
3. Allowing exclusive mode to devices has always been unchecked in Windows settings.

Audition (v4) has only two modes available (MME and ASIO), and up to the point of running SONAR in WDM mode they have never even seen each other. I am a bit baffled as to why WDM mode in SONAR is causing this, but seems an active WDM connection is precluding MME access to the chip. Any insights on this one?