For this last setup: one dedicated device using the MT as “wifi adapter”, the “station-pseudobridge-clone” mode is the most logical to use.
Maybe you had this earlier in a working condition, but are using a different device now (so there is a different MAC address to be set as clone, or none must be set)
“station-pseudobridge-clone” - similar to the station-pseudobridge, but the station will clone MAC address of a particular device (set in the station-bridge-clone-mac property), i.e. it will change itsown address to the one of a different device. In case no address is set in the station-bridge-clone-mac property, the station postpones connecting to an AP until some packet, with the source MAC address different from any of the router itself, needs to be transmitted over that interface. It then connects to an AP with the MAC address of the device that have sent that packet
More found here: http://forum.mikrotik.com/t/station-pseudobridge-in-3-x/21267/1