what signatures did you get ?
I think there is a special rule that re-roll works only for craftable cards.
For example Signature C’thun don’t triggers re-roll wiht normal C’thun becouse normal C’thun is assigned for free by opening a Whispers of the Old Gods pack.
edit: another example is Signature Cenarius , Cenarius is currently in Core rotation so you can have the Core unlocked temporary version in collection but not the real ones , so in this case Signature Cenarius can’t find the other low rarity Cenarius (Legacy set) and re-roll will not trigger.
but i can be wrong im not totally sure of this “hidden” rule.
Signature can drop but should re-roll if not some special case
edit2: i can’t find your bundle but another one but seems like it targets signatures from badlands and titans so what i write on top can’t be possible , but just a general rule.
edit3: but a card like Sheriff Barrelbrim Signature can’t re-roll i think , the normal Sheriff is assigned for free to anyone, and the gold Sheriff is uncraftable but only earnable after purchasing tavern pass.