FriendsInSpace got that fixed. It was due to Orc/Gnome having a reduced pop requirement for building which isn't divisible in a whole number by the buff provided by Carpentry, which resulted in a fraction, which was then getting rounded down, which would then result in you being short by 1 peasant to have the number of buildings you wanted to build.
A funny way of seeing it in action was to just put 1 building on build, which would assign 73 peasants/0 buildings buildable, short by 1 peasant.
Should be good now 🙂