Unable to whip 3 to 1 Pop

[GooglyBoogly]

I have a 3 pop city called Pasargadae with a 25/60 granary in the production queue (at normal speed) and am running slavery.
But. THe whip button will not allow me to whip it, it says that it requires 2 pop, which the city has spare, bit then states that max availiable is 1.

I am running BTS 3.17 with Solvers patch (0.19) the BUG MOD 3.0 build 945 on top of that.

See screenie and attached file if that is not enough.

 

[Husyor]

You can only do up to half your population at any one time (rounded down), thus half of 3 is 1.5 and rounded down is 1. Been this way since vanilla as far as I know.

 

[GooglyBoogly]

Thanks. Husyor, My mistake.