Cannot Bind to asp:Dropdownlist in Bootstrap Modal - asp.net

Question

For some reason, I cannot bind to an asp:Dropdownlist inside a Modal, and I can't figure out what I am missing. If I move the dropdownlist outside of the Modal, that data binds perfectly, but inside the Modal, the dropdownlist is always blank. Can someone please tell me what I am missing here:
Here is the Modal:
<div id="copyEmployeeModal" class="md-modal colored-header md-effect-9 prmiary">
<div class="md-content">
<div class="modal-header">
<button type="button" data-dismiss="modal3" aria-hidden="true" class="close md-close" onclick="return CloseModal();"><i class="icon s7-close"></i></button>
<h3 class="modal-title">
<asp:Label ID="lblcopyEmployeeModalTitle" runat="server" Text="Copy Employee Permissions"></asp:Label>
</h3>
</div>
<div class="modal-body form" style="padding: 0px!important;">
<asp:DropDownList ID="ddlNonGroupEmployees" runat="server" CssClass="form-control" AutoPostBack="true"></asp:DropDownList>
</div>
</div>
</div>
Here is the code to bind the dropdownlist:
ddlNonGroupEmployees.DataSource = GetNonGroupEmployees();
ddlNonGroupEmployees.DataTextField = "DisplayName";
ddlNonGroupEmployees.DataValueField = "EmployeeId";
ddlNonGroupEmployees.DataBind();
I know the above code has data, and as I said if I move the dropdownlist out of the modal and place it on the page, the data binds to the dropdownlist with no issues. Can anyone tell me what I am missing here?
Any assistance is greatly appreciated!