Getting 'group' into a submodel

[Roland Melkert]

The file was an LDR so it won't provide the option to create a submodel in the mpd since it's not an mpd.
The solution is to add one empty submodel which converts the ldr to an mpd and then the function works.

That's very very (very) weird as the dialog has no limitations on when to allow mpd selection or not. Or did you mean the whole dialog won't appear?