While editing the first-person hand position of a model, the "FP Hand Position" menu allows negative numbers in the fields for x, y, and z rotations; however, if any of the three are set to a negative number, that rotation will not persist when the model is saved, exported, or reloaded.

Steps to reproduce:

1. Create a new CPM model with a distinct hand shape in the in-game editor.
2. Click File > Test Ingame to access the FP Hand Position menu.
3. In the FP Hand Position menu, set any field for rotation to a positive value, and note the position of the hand model.
4. Set any other rotation field to a negative value, and note the new position.
5. Return to the in-game editor and save the model.
6. Click File > Test Ingame again, and note the position of the hand (it should now be at the same position as in Step 4)
7. Return to the FP Hand Position menu, and change the negative value to an equivalent, positive value (i.e -30 -> 330). Optional: make a small change to the value first; the model should jump to a position near the position in Step 5.
8. Save the model once again.

The hand position should now work as expected, and be in a consistent location (the same as in Step 5) regardless of saving/exporting/reloading the model.

I've tested the following versions, and experienced the issue on both: 1.12.2 v0.6.14a, and 1.20 v0.6.14c