So, just upgraded from SW14 SP3 to SW16 SP3.  Clean install, no settings imported from the previous version, as absolutely stock is as possible to be.  Everything seems to be running okay, except I can't seem to load the Flow Sim add-in.

It's shown as licensed in the "My SolidWorks Products" tool:

I can see free licenses in the license manager:

But it's greyed out on Add-ins toolbar:

And isn't in the Tools > Add-ins menu (where it used to be in SW14).

So, am I missing some other box / button / menu / incantation / animal sacrifice to get Flow Sim enabled in SW16?  Or is there something lurking / missing in my install do we think?