Iaxy one way audio from Zap incoming

I have a strange problem here. This has been replicated on Asterisk@home 2.7.and 2.8 with both a TDM400 and an X100P by myself and by a friend on another A@H system. My setup:
A@H 2.8 on an internal LAN, 192.168.0.xxx,
Iaxy provisioned on the same internal LAN along with several SIP hardphones.
X100P Zap interface (also tested with TDM02B)

If I receive a call from the pstn over the zap channel and answer it with the Iaxy box, they can hear me, but I can’t hear them. If I MAKE a call from the Iaxy over the Zap channel, everything works fine. All other combinations of Zap, SIP and Iaxy work fine. Incoming from my VoIP provider via SIP to Iaxy works, incoming from Zap to SIP works, internal SIP to Iaxy and Iaxy to SIP works.
Further testing showed a strange anomaly: If I answer an incoming Zap call with a SIP phone and transfer it to the Iaxy I still have 1 way audio, but if I park the call and pick it up on the Iaxy I have 2 way audio!
Anyone have a solution :question:

Thanks, Mike

Tried it yesterday with an IAX softphone to verify or eliminate IAX itself as the problem. IAX softphone works just fine, 2 way audio everywhere, so apparently it’s just a problem with the IAXy. I’d REALLY like to use my IAXy as an ATA :frowning: