In Pro 2.2.1, that code appears if the field it grabs to display has one or more spaces in it. If it is truly blank, it displays <empty>. If it is NULL, it displays <null>. It only shows this code if there are spaces. If seems to be grabbing the first field that has the word NAME in it, or if none, then it grabs an ID field. I guess the workaround is to make sure you don't have spaces in your data!
Cathy