Double checked, With before updated dmxAppConnect.js version is working. with updated our drop downs are dead.
Below Dropdown code.
Binded to "custom database query
`<select name="file" required="" class="form-control custom-select" id="file" dmx-bind:options="SupportedDataFiles.data.GetSupportedDataFilesCustom" optiontext="'FileID-'+FileID+' '" optionvalue="FileID" readonly="true" rel="">