Exactly.  You have to be in the Material Room to apply a Material Collection.  A minor shortcoming but worth that couple of extra clicks.

Now, you mention you use D|S, too.  Oh well, you'll have to convert them to MAT poses.  Easy enough to do with Wordpad:

Open the MC6 in Wordpad.

Change the version from 6 to 4

Change mtlCollection to figure

Save as .pz2

Move to the Pose Library, along with whatever PNG is associated with it.

 

That's all there is to it.  I can't be bothered to do it because, by and large, it gets to be a pain in the nether regions to edit 50 or 60 of them, even doing a search and replace.  I generally trust people to have enough sense to know how to use them as they are. 

Coppula eam se non posit acceptera jocularum.

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