update: I reinstalled x-plane and new install of TBM, and still didn't work. I then created a NEW airframe, and that worked. I can't explain it... but it works.
Thanks for your help.
I can't seem to find it in the instructions - on the TBM900, in the maintenance manager, the oxygen bottle refill button is grayed out so I can't refill it, and, the inplane oxy psi gauge is showing a red "X" on the MFD. Is this normal or am I doing something wrong?