Created Unassigned: Combobox: list moves when zooming or scrolling on mobile [27670]

Dear,

When putting a combox in our webapplication, it works great with pc browsers.
However when i try to use it with a mobile (tested with android and IOS) the location of the combobox moves when i zoom or scroll through the page.

It seems the list is not fixed tot the control.

my code:
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
<asp:ToolkitScriptManager ID="toolkitScriptmanager" runat="server">
</asp:ToolkitScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:comboBox ID="ComboBox1" runat="server"
DropDownStyle="DropDownlist"
AutoCompleteMode="SuggestAppend"
CaseSensitive="false"
RenderMode="block"
ItemInsertLocation="Append"
ListItemHoverCssClass="ComboBoxListItemHover">
<asp:ListItem>test</asp:ListItem>
<asp:ListItem>test2</asp:ListItem>

</asp:comboBox>

in CSS i've also put: .ajax__combobox_itemlist{
position: fixed !important;
}
this fixes the fact that the list starts at the wrong place