The User guide PDF suggests three reasons, but doesn't explicitly say how to solve it:
1) "There is no variant information in the lower-level block (reusable block)."
>I have created variant data for my lower level block. I then copy and paste the lower level block's windows folder into the worklib of my main project. Is that enough?
2) "Variants are not defined for the top-level block."
>What does this mean? That I need to create variants for my top-level block as well? Why? I did this, doesn't make a difference.
3) "The block has not been identified for hierarchical variants."
>What does this mean?
bump. does no one use this feature?