CNC control software includes a set of machine-dependent parameters that define things like "steps per mm" for the different axes, max speeds and acceleration, etc. One parameter is direction to move on homing. Don't know which generation of Tormach control software you are using or whether these parameters are easily accessible or locked away in some hidden area but that's where I would be looking. I presume that you load a different set of parameters for milling or lathe modes?

Is it possible to look at the machine parameters to check? Maybe compare mill and turn mode settings?

Quite plausible that there are limit switches at both ends of travel, though, or even one switch with two triggers. My own mill only has switches at one end for homing and I rely on soft limits at the other end.

Actually though I always re-home the X axis on the lathe on startup it's usually within a fraction of a mm, which I put down to the non-integer whole step being lost when the drivers power down. I only re-home to make sure my tool offsets give the right diameter.

Likewise on the mill, I generally find that on power up the actual position of the spindle closely corresponds to the DROs, though I generally re-reference to the new workpiece. When I was doing a lot of rotary axis stuff doing CNC knurling where the Y axis is referenced to zero along the rotary axis, I found that the Y axis setting was preserved when powering down and up again. I very rarely "home all" as apart from giving a reference for soft limits it has no useful function. I do all my work by referencing to the workpiece.