Domain mapping and Supporter plugin

Just a question relating to the Domain Mapping plugin. I've placed Domain Mapping plugin in mu-plugins folder as suggested in the install instructions. I also have Supporter plugin working well - however - when I go to the premium plugins page (under Supporter) - the D. Mapping plugin isn't showing in the list even though D.M. instructions say it can be enabled as a premium plugin from here.

It seems that the only plugins showing up on the Supporter plugins list are from the /plugins/ folder not the /mu-plugins/ folder.

Should I put Domain Mapping plugin in the /plugins/ folder????