A test

The first custom checkbox if not set to default, the second one is. I have ticked both and am saving to then edit again. Interesting stuff isnt it?

Now ive edited them both unticked.

Now Im just ticking the first one

Aha. Think I have finally reproded it. Last edit was first one ticked, second one unticked. I have just edited again and they are both ticked. Ill try again. Yup. Its saving correctly though. Ill try a couple other combos.

OK. only time I can get the bug is on a field where the checkbox is set to default, but is unticked but the other is ticked.