Follow Up Strike doesn't work with versatile weapons

Well, you mean according to the description. 

Since it is a homebrew by the devs, maybe they like it that way (if so, they could tweak the description if need be). 

I think it is fair/balanced, as using two hands means you are not holding a shield notably.  I think it's cool that it works with versatile.

Not a bug, it is by design and a one-handed weapon held in two hands (versatile) is not the same as a two-handed weapon.