I don't think so, this is one step checkout page (default kentico), I also facing this issue on contact form of Corporate site and any other custom site/form of Kentico 8.
Sometime I can go to next step by remove this field and create a same one.
I have passed this K8 setup to 5 persons for testing. 4 persons was met this issue like me, only 1 guy is NOT. I dont know why, it's very corking.