There are a couple of problems I am seeing. Note that I am on a machine under OS High Sierra. Mac Pro Late 2013
If in a Form’s Graphic Mode in the Text Editor Options window and you enable the Pop Up Editing check box with Mode Field/Variable and then go to the data mode problems happen.
The form incidentally was created using the Construct Menu Pull Down for Fields and Variables.
If you change or enter data on that form cell it does not happen. Within the cell you can see your entry but upon tabbing out or mousing out the data is lost. Looking at the datasheet the change is not shown. Like it never happened
If you go to the cell on the datasheet and edit of add data indeed the change is registered on the datasheet but NOT on the Form.
If you go back into the cell via the Form and double click the cell you can see the change that was made on the datasheet but when you exit the change reverts back to what was there before the change was made.
Then if you go into the Graphics Mode and then The Text Editor Options and uncheck the Pop Up Editing box and go back into the Data Mode you cannot edit the cell. Going back into the Graphics Mode on the form, clicking on and highlighting the cell, then going to the Top Menu, Objects Menu (7th from the right of the Apple Menu), Arrange Submenu, then “Bring to Front” it fixes the form.
And like the commercial for water damage “it’s like nothing ever happened”.
Back to Data Mode and the cell can be edited or change and it shows up on the datasheet.