MII_TRANS_PLUGIN Input XML empty

Using the ME activity MII_TRANS_PLUGIN to call an MII Transaction directly from a POD button, when selecting an SFC and Operation, then clicking the button associated with this Activity, the Input XML passed to the Transaction is empty.

What configuration is required to define what the contents of the Input XML should contain? Is there a standard content that for some reason the system is failing to generate?

The MII_TRANS_EXT and Service Extension processes all work as expected, but the MII_TRANS_PLUGIN seems to not work.

Is there a way to directly call an MII Transaction from the ME POD via a button click without calling this from the Service Extension process?