Hi Dave and fellow simmers,
I have this problem that seems to involve just the Socata TBM, but I present it here in case anyone has an idea. Here it is:
A few days ago I began to notice that Pilot2ATC was behaving strangely. On starting it, it wouldn't finish an ATIS report, stopping after a few words and then starting again. Finally, after getting clearance, the tower tried to hand me off to departure and after departure started to respond, tower came back and tried the handoff again. In short, the control would not pass to the next frequency. When the plane was stopped the frequency would swap back and forth between the COM1 and COM2 (which is why ATIS could never finish.) Then today, I had a flight in the Eclipse 550 where everything worked. Hmmm. Then I started a flight with the Socata and the problem was back. So I disabled all AI aircraft and turned off some other plugins that used the voice system. No cure. Then I changed to a plane that wasn't the Socata. Problem fixed. Back to the Socata, back to the problem. Pilot2ATC, Reality GTN 750 and the Socata TBM900 are fighting over the radio controls. 
Pilot2ATC is configured as always - I've used it for several years....
Reality GTN750 I use as a floating window in all my planes since I fly in VR and can control it easily with the controllers. When I saw this problem emerge, I updated to the latest version of the GTN. I even copied the RealityGTN.ini file to the Socata from the Epic 1000 where it works just fine.
The Socata is the variable that causes the problem. Any other plane works with the other 2 program settings identical.

There are some planes, obviously including your Socata, that do not implement their Comms in the normal way, so P2A cannot control them.  In most cases, you can manually change frequencies from the cockpit, but your copilot will not be able to mange the radio frequencies for you.

Dave

I've got the TBM 900 and my radios work fine, I suggest that it may be the GTN 750 that is causing problems in your case as the TBM and P2ATC is working fine for me. I do have the RXP GTN 750 but dont use it with this aircraft as it had been causing crashes for me in combination with this aircraft.

I turned off the GTN 750 with XOrganizer so that it wouldn't load when I selected the TBM. I will try removing it's folder from plugins and report back... 

I am also having the same problem with the Com 1 switching over to com 2. I am using Xplane 11 Zibo 737.  I use opencockpits Com module. Any workarounds ????

P2A interacts only with X-Plane via XPUIPC.  I suspect the Com Module is telling X-Plane to do something and that is not being passed on to P2A.

I suspect with your setup, you will need to make all radio changes with your Com Module, rendering the P2A Copilot unable to set the radio.  

I too had this problem but found restarting the sim worked for me. It was in the Tbm900.

It is embarrassing to admit that this problem has been solved for a while now and I don't even remember how I did it - or even IF  I did it. Sorry!

I had the same problem and disabling the GTN 750 fixed it for me.

I have experienced the same problem with different aircraft and more so in MSFS.

The config p2a setup option for "Reverse Com Channels" seems to influence this result.   Try reversing whatever it is presently.

I also would click on the desired com in my case com1 that is right beside STBY on the lower left pane might help to get it to stick.

I have ignore avionics and battery disabled.

In msfs I fly H145 which use com2.