Not sure if a bug: Gambit Singature doesn't raise Rating

Patcha_it

Hi all,
not sure if this is a bug, but I noticed that raising Gambit's Signature Ability with duplicates or Crystal, doesn't grow at all his rating value.

Is it a bug or it is normal as expected?

te_dua_shum

for 4 stars or lower rarities it's normal, his Pl is the same at sig. 1 and at sig. 99, but it should change for 5 and 6 star versions ^_^

Patcha_it

Well seems it's a known stuffs, but still sounds odd...