zeno clash 2 from humble bundle is showing as Zeno Clash 2 Special Edition

Huh, really? Mine is showing as Standard, and thus, no bonuses.

The Special Edition for Zeno Clash 2 includes:
‘The Art of ‘Zenozoik’ digital artbook

Zeno Clash 2 Original Soundtrack

nothin' special (btw we can download ost from humble)

synced my account it shows special edition and when i try to buy special edition it shows i own it :)

try to buy special edition upgrade.
my ZC2 from HB are standard version.

I'm guessing there was a soundtrack code in the bundle that you redeemed ?
Since the soundtrack isn't listed separately on Steam, but is part of the special edition, it could be that the key you get is for the upgrade package.