maximenu mobile and compression - Iphone 4

Hi Guys. We are using the JCH Optimize Pro Plugin, since our template did not came with any compression option. Now we have discovered an issue which only shows up on IPhone ( 4 and newer). If we turn on the Plugin (all configurations, from basic to optimum) ... which basically compresses .css and .js files and further .. we see suddenly a "white" bar on top of the maximenu mobile. See screen. On Android it shows fine after the plugin is activated, but not apple. The plugin allows to exclude by module resp. component, but that does not fix the issue. Ideas ?

web124.login-8.loginserver.ch/cms/

Hi
Unfortunately I can not debug something that is changing the way the things are loaded, and more if this happens only with Apple
CEd