I am not familiar with the product you used, but it sounds as though it is one of the leather 'paint' products used to put a coating on lower grade leathers. I would suspect that the cracking is due to it being incompatible with whatever finish was previously on the leather.

I believe there are products designed to remove such 'dyes' but I don't know the name of any off hand. Perhaps one of our professional leatherworkers can help.

The products others have mentioned above are penetrating dyes, like wood stain. They would not work if the boots already have a coating type finish.