When we first got the feature of 'placeholder' text in a text field people sometimes would use this to display data using the placeholder calculation. Often times we might have a single global field that appears on a layout more than one time to show different bits of information.
I noticed today that if you have the SAME field on a layout more than once, you can ONLY EDIT THE FIRST INSTANCE of PLACEHOLDER text in the inspector. If you have more than one instance on the field you will not be able to edit that in V16.01.162. I've noticed that in v16 the calculation will still work for the same field displaying different calculations in v16 but you cannot edit them there. You'll have to go back to v15 to edit the details.
This may cause some update issues for people who have used this placeholder text UI methodology.
Attached is a test file so you can try to replicate the problem. Open it in FileMaker 15 and you'll be able to edit both fields placeholder text. In FileMaker 16 you will only be able to edit the first instance of the field that had placeholder text.