If you wear a Graviplas helmet (which is a hat) and an actual transparent helmet, your facial hair is not shown.
ARMA 781f5 - AA_Clothes_UtilityOveralls_Welding_Helmet_01 - Incorrectly has flags 17 - Beard and 18- Neuroamp set. These should be removed. Compare to ARMA 16e0c4 - AA_Clothes_Stealth_Helmet. This is another ARMA for a helmet with opaque face that is flagged as a hat. There are no other ARMAs that have this issue.
Yes, I can recreate this issue.
Create character with facial hair. Equip 781f7 and 1e2b17 (or any helmet with transparent face shield at the same time. ARMA 781f5 Fix.zip ~Wartortle