You've got two things going on that are incompatible with each other.
If you are plugging that 1/8" mono connector straight into the mic input on the front then you are shorting out the PTT circuit, which when Mic is selected at "Tip", then PTT is assigned to "Ring". Thus I'm guessing you went into General > H/W Select and set PTT to OFF. If you do that then no PTT input will work because the mic and rear panel inputs are wired in parallel on the Orion MKII board. IIRC, that they are wired together is not covered in any of the manuals
The solution is that you have to make a mono to stereo (TRS) adapter. Mono tip to stereo tip. Mono ring/shield to stereo shield. Stereo ring not connected to anything. Then enable PTT in setup.
This is probably the number one error made when interfacing a mic into an ANAN. The number two mistake is using a mic that has separate bias and mic connections on tip and ring. This is typical of computer mic's and also requires an adapter to sort out.
I'll be moving this discussion to the mic sub-forum in a day or so.