I've just experienced some rather odd behaviour on a popover. It worked fine in FM13, but not in FM14. On entry of data into the second field (of 2), both fields, and their labels, simply disappeared. There's no "hide" behaviour set, or conditional formatting, and Data Viewer shows that they retain their values, but they were just not visible.
It turned out that the tab order was to blame - the next field in the order after the second field on the popover was a field on the main layout. Removing the tab order resolved the problem, but I thought I'd mention it, as it confused me for a while.
And BTW - thanks Filemaker for finally offering check marks in checkbox sets!