When you configure a Virtual SSID to be member of a bridge, Zeroshell automatically set the variable bridge=BRIDGE00 in the hostapd’s configuration file and set WDS=1 for the VAP by using iwpriv.
I think the your wifi card could be not 100% compatible with MadWifi modules.
Do you have tried with plaintext instead of PSK?
Do you have tried with another client with a different wireless card?
Regards
Fulvio