What is the best way to have a lookup that supports creating a new record if one isn't found?

One issue I’ve found after using this in production is that you HAVE to choose a value in order to close the pop up window. And once you’ve chosen a value, there’s no way to clear the field. I tried creating a Global Action in the table that would enter a blank value in the field, save the model, then close the popup, but it just doesn’t work, it never closes the popup. I even tried Redirect to Url so that it would refresh the page but it just hangs. 

My current solution - I added some template text “Note: You must choose a Loan Officer” that renders conditionally if the field is blank. 

Once the field is populated, you can open that edit window and close it without choosing a new value.