I have been doing some testing on some forms to show a field when another field that is populated with a lookup comes back empty because it has more than one value returned (see this post).
While testing this, I have discovered that if I have a normal single line field and a lookup comes back with more than result, I can click into the field and select from the available values. However, if I add text above or below the field using the field settings, I am not presented with a list of values to select from.
I am using Forms 9.2.0.908.