Does this happen to anyone else?

It's probably closer to Tech + Style - (Hit * 0.25) if you're going solo. The formula is different for Hit while in parties, probably 0.125 instead of 0.25.

I think this is how it is:

SSS = 105
SS = 95
S = 85
A = 80
B = 75
C = 70
E = 65
F = 60