I updated my asp.net solution from 14.1 to 15.1 using the version utility. 

Now my dynamically loaded combo boxes do not expand. 

The code below does not expand.

Here is my aspx code. it is in a table in an asp:panel

<ig:WebDropDown ID="WebDropDown1" runat="server" Width="280px"
    DropDownContainerHeight="0px" DropDownContainerMaxHeight="150px" PageSize="0"
    AutoFilterTimeoutMs="20" Font-Bold="True" Font-Names="Verdana" Font-Size="8pt" 
    Height="25px" Button-Visible="True" AutoFilterResultSize="50" 
    EnableAutoFiltering="Client" EnableViewState="False"
    ValueField="InstTypeID" TextField="Description">
    <DropDownItemBinding TextField="Description" ValueField="InstType" KeyField="InstType" />
    <DropDownItemBinding KeyField="InstType" TextField="Description" ValueField="InstTypeID" />
ig:WebDropDown> 

Here is the code behind that fills the items.

// Fill the Instrument Types dropdown list 
WebDropDown1.Items.Add(new DropDownItem("", ""));
foreach (string[] instData in from getInstrument in vDS.getInstrumentTypes() where !string.IsNullOrEmpty(getInstrument) select getInstrument.Split('-'))
{
    WebDropDown1.Items.Add(new DropDownItem(instData[2], instData[0]));
}

The code below does expand normally.

Here is the aspx code.

<ig:WebDropDown ID="ddMapType" runat="server" AutoFilterResultSize="50" AutoFilterTimeoutMs="20" 
    AutoPostBack="false" AutoSelectOnMatch="False" Button-Visible="True" 
    DropDownContainerHeight="0px" DropDownContainerMaxHeight="400px" EnableAutoFiltering="Client" 
    EnableCustomValues="False" Font-Bold="True" Font-Names="Verdana" Font-Size="8pt" 
    Height="25px" PageSize="0" Width="229px">
    <Items>
        <ig:DropDownItem Text="Maps and Plats" Value="1" />
        <ig:DropDownItem Text="Record of Survey" Value="2" />
        <ig:DropDownItem Text="Road/Highway Maps" Value="3" />
    Items>     <ClientEvents /> ig:WebDropDown> 

This page as well as all my other pages used to register their infragistics Assemblies on each page.

After update all assembly references were moved to the config file 

I don't know if this makes any difference.

It then removed the references from the individual web pages.

The dropdowns are definitely populated since I can use the

down arrow to scroll through individual items in the dropdown.