Question; is the FD blood w. too big/long? If it's too big, your bettas are too young. Young females would fight like males when jarred. The females would show bars like the breeding bars - but she isn't in a breeding mood. This might be your problem.
I suggest you wait until they are big enough to gulp down BW whole..... or at least 3cm (body only).
To get them off flakes, you could exclusively feed mosq. larva for 3 days. They should get over flakes. Must warn you though, they may not want to eat anything else - you may need to starve them before they'll eat other food.