in version 12.05 the placeholder don't, my field Type is Date and placeholder is 'mm/dd/yyyy' but version 12.05 generate:
<input type="text" name="Mem__FechaNacimiento_DATE" id="Mem__FechaNacimiento_DATE" value=" / /" class="nt-lookup-entry nt-entry ui-corner-all nt-entry-required hasDatepicker" data-nextfocus="Mem__CorreoElectronico" style="width: 16em;" placeholder="mm/dd/yyyy" data-do="imm" data-formproc="updateperfil">
in version 11.43
<input type="text" name="Mem__FechaNacimiento_DATE" id="Mem__FechaNacimiento_DATE" class="nt-lookup-entry nt-entry ui-corner-all nt-entry-required hasDatepicker" data-nextfocus="Mem__CorreoElectronico" style="width: 16em;" placeholder="mm/dd/yyyy" data-do="imm" data-formproc="updateperfil">
i think that the value is a problem.