fine
All the kicad 3d library models are made as single object. This is an approach to simplify the tree of the board... i.e. a chip is not a body plus hundred of pins... it is just a single object (this is an approach adopted also from many manufacturers)
StepUp is informing when there is a model which is not following the standard approach.
My mac mini had a GPU failure few time ago and now I don't have any mac to test the tool on.
Mainly StepUp seems to work just fine on mac, but I heard from some user that it could be a drivers issue.
Unfortunately I have no way to test it on a mac.