Final Furlong Breeding Question

I don’t know if this is a bug but suspect it might be.

I have four stallions who had open breeding slots for June 2 which were not filled by FF-owned mares.
NCh. Away The Lads (
NCh. Last For More (
NCh. LiveLong&Prosper (
GCh. Superdocious (

Of these four, three of them (NCh. Away The Lads, NCh. Last For More & GCh. Superdocious) all had two open slots for June 2. In each of these cases, one of their June 2 slots was filled by a FF-owned mare, but not the other.

We had another stallion, NCh. Hogwarts (, who also had two open slots for June 2 but, in his case, both slots were filled by FF-owned mares.

I thought that if you set up a stallion to allow FF-owned mares, any open slots for the most recently ended period (in this case June 2) would be filled by FF-owned mares.

I’m just curious as to why all open June 2 slots for NCh. Hogwarts were filled by FF-owned mares, but not the other four?

Only two of my boys had open slots in June, but they both show that no mare was booked for one of the June 2 slots, too. Bear Witness had 1 private mare and 0 FF mares for June 2, and Ducati had 1 FF mare booked from 2 open slots for June 2.