This is the typical behavior in 2011 - not just UR12.
You can make the field clickable with some JavaScript:
function OnLoad() { //Readonly form if (Xrm.Page.ui.getFormType() == 4) { //Enable field Xrm.Page.ui.controls.get("websiteurl").setDisabled(false); //Even though for is read only - this removes the pop up asking you save //when closing the record if the field changed Xrm.Page.getAttribute("websiteurl").setSubmitMode("never"); } }