Option Buttons on Form not loading data

[newbie on LO - go easy]
I have a boolean field in a table, to indicate gender. In the corresponding form, I have two option buttons, grouped. Adding a record and setting one of the buttons (I’m using true for male, false for female) correctly sets the field in the table. However, when I scroll through the records on the form, neither of the buttons is selected. In the control properties, one button has reference value (on) of 1, the other has reference value (on) of 0. Reference value (off) is blank for both.

What am I missing?

Did you ever find a solution? I am having the same problem after upgrading to 5.4xxx version from older 3xxx version.