@James, thank you for your tip. I will finish this project with the 1.8 version. I will try to debug it later. But i hoped the ACF had a earlier bug report of this.
@jgraup i am using WPML as multilanguage, just tested it with a WordPress installation without a multilanguage plugin, that’s seem to be working. So it’s clear what causes the problem, now we need to know which file, HA!