Its impossible for me to get Antimatter

[jojo7x7jojo]

I buyed the Blank Vouchers over 20 times and but unfortunately it doesn't unlock for me and that's particularly annoying because I don't get the 100% achievement

[malogoss]

To add it to your collection, you need to buy the Blank voucher and buy Antimatter (if unlocked) too, both in the same run. You can go endless if you want, it counts too.

[TimTim3000]

I just now had the opposite problem lol. Got Blank in ante 1 and Antimatter popped up in ante 2 but I had no cash left :(

[Stormy]

Do you mean you're never rolling it in the shops, or that it's not even unlocking to begin with?
If it's the first, it's just bad luck
If it's the second, you're buying blank vouchers in seeded/challenge runs, and nothing counts for progression in either of those (aside from achievements for completing the challenges themselves). You need to buy the blank voucher ten times in unseeded normal runs.

[SamTheSandwich]

Also, if you buy Blank during challenges, the number goes up but it doesn't actually unlock