When using the MCB in the "2 x 32-bit bidirectional and 4 x 32-bit unidirectional" port configuration, port 3 (P3) can only be used in write mode. There is no support for P3 read mode.
Solution
This will be resolved in IDS 11.4 (MIG 3.3). Until this time, port 3 must be used as a write-only port when using the "2 x 32-bit bidirectional and 4 x 32-bit unidirectional" port configuration.