Only let you build ships, not GFs
#chaos mapping buttons
paper wraith
warped pumice
I think it's because you're in a system with no planets? Because I used that button recently exactly to build a Mech on a planet, and remember seeing that there's no option to put the Mech in space.
clever briar
Yep, will fix this probably today. Similar problem with any ability that wants to produce infantry in space