That point is where the shoe flexes when walking so there will always be cracking in that area.
I would always recommend thoroughly wearing in a new pair of shoes for as long as possible before bulling (though that's not easy when it's your only pair of parade shoes and they only get worn two evenings a week).
The photo above was for a customer who had not been able to get them as broken in as they would have liked in time. I can guarantee that those would have cracked as you describe after the first wearing. The customer accepted this.
The trick to coping with it is that once the shoes have developed the natural wrinkles in the leather you apply less polish to that area. They can still be made to shine but the shine won't be as deep and glass like as the rest of the shoe.
That's fine. With the wrinkles there it would never appear glassy anyway.
If I'm bulling up for a parade I might apply a little more but I would expect to suffer the cracking and will simply repair the shine again afterwards. Fine wire wool to remove the flaking polish and then re-bull.
Remember though, a working pair of shoes will get worn regularly and those wrinkles behind the toecap are expected and acceptable.
If you're going for a full-on shine like those above don't forget to also devote a little time to the edges of the rubber soles. They bull-up very easily, particularly around the heel.