Try adding an IP to the bridge, It seems like one of the cases where It Is actually needed, as the IP assigned to a port which Is part of the bridge has "less dignity" see here:
L22UGS-5HaxD2HaxD Layer 3 a standalone access point
starting here:
L22UGS-5HaxD2HaxD Layer 3 a standalone access point - #7 by jaclaz