Problems Hueman with ShiftNav

Hi everyone,

since the update to 3.3.8 i´ve got a problem with the expanded search in my topbar navigation. For the mobile version of my site i am using the shiftnav pro off canvas menu. I´ve got this included before my toggle:

<div class="toggle-search"><i class="fa fa-search"></i></div>
<div class="search-expand">
<div class="search-expand-inner">
<form method="get" class="searchform themeform" action="http://xxx.de/">
<div>
<input type="text" class="search" name="s" onblur="if(this.value=='')this.value='Suche';" onfocus="if(this.value=='Suche')this.value='';" value="Suche">
</div>
</form>        
</div>
</div>

Since the last updates and the header changes that were included with it, the searchform doesn´t open anymore in the mobile view.

Do you have any suggestions, what could be the reason for this problem?

Best regards
Dominik