Cannot append or replace metadata for DNG files greater than 1GB

Bridge will not allow me to append or replace metadata to a DNG file that is greater than 1GB. Ifa I select tools -> append metadata template or replace metadate template, the metadata templaces are greyed out. If I select an individual metadata item and attempt to type a value in it ("Descripton"), I get "This property cannot be modified." This does not happen on DNG files under 1GB in size and it happens regardless of whether I tell Bridge to use .xmp or .dng file for the metadata. This is on Bridge 11.1.1.185.