I have a typical floor for a tower and have skinned it with 8 curtain wall groups.

I am trying to use design options to show two iterations of windows and thus, I have created two design options for a series of stacked floors and am trying to move the groups from the main model to option 1.

two of my groups however are not co-operating. they want only to be hosted in the main model

any ideas why?

as background:
- all groups are referenced in top and bottom height only to their host floor
- all groups do not have any model in place components