Add to "Temp HP"; Pathfinder Buff; Official PF1 sheet, Pathfinder by Roll20 version 1.303

Add to "Temp HP" Pathfinder Buff - Character is called Gretchen This works (+64 to temporary HP;) but when the buff is removed the 64 stays, so I tried a Debuff_64, (-64 to temporary HP;) to subtract the 64, and it does not work,  Why is Roll 20 so broken? This works (+8 racial to perception;)  and the 8 is removed when the Buff is removed

Pathfinder Buff; Official PF1 sheet, Pathfinder by Roll20 version 1.303 This works for HP, +@{level}*@{constitution_mod} to HP; Trying to get this to work for Temp HP,  Subtract the amount that is the Temp HP to reduce the amount to 0  This works for Temp HP to add it +51 to temporary HP; +(6*@{constitution_mod}) to temporary HP;   or +51 +(6*@{constitution_mod}) to temporary HP;   but to subtract, it does not work -51 to temporary HP; -(6*@{constitution_mod}) to temporary HP; Does not work -51 -(6*@{constitution_mod}) to temporary HP;   Does not work -@{hp_temp} to temporary HP;  Does not work  +@{hp_temp}*(-1) to temporary HP;  Does not work any help?