In ROS bridge has multiple (more or less distinct) functions, one is CPU-facing bridge port and you have to configure it properly to allow ROS to interact with VLANs which are passing bridge switch-like function. VLAN membership of CPU-facing bridge port is done the same way as for other bridge ports.
More about different bridge functions: http://forum.mikrotik.com/t/routeros-bridge-mysteries-explained/147832/1