Form Fitting body armor...
 

I was transfering a character from paper into Hero Labs last night and when I added the Form Fitting Body armor it did not halve the weight as it was supposed to.

The rules say that Form Fitting body armor only counts half of it's weight rounded down when combined with other armor.

Character is wearing an Armor Jacket (8) and full suit of form fitting body armor (3) and a helmet (1)

This should be 8+1+1 = 10... but in Hero Labs it comes out as 8+3+1 = 12 which encumbers the character.

What am I doing wrong?

Did you mean the form fitting shirt, which has a baliistic armor value of 3, and therefore adds 1 to encumbrance, or the full-body form-fitting suit, which has a ballistic armor of 6, and therefore adds 3 to encumbrance?

I just tried tested the combination of armors you listed, and with a form-fitting shirt, the calculations come out as you say they should, and with a form-fitting suit, they come out as you say they currently are.

No you are absolutely right... just reread it from both the core and from Arsenal and the Full body suit would add half of it's rating to the 8 from the armor jacket making it an 11... my player was trying to convince that it should be half of 3... instead of half of 6.

Time for player chastizement