Hi there,
After going back and forth with Ninjaform support it appears some GP theme CSS is conflicting with Ninjaforms’ tickbox. NF support said Ninja Forms inherits and defers to the styling rules put in place by the theme. This is confirmed by switching to the default Twenty Twenty-one theme.
Radio buttons work fine, just the checkbox doesn’t check properly (whether visually but also data-wise, it doesn’t record as ticked).
Any idea what GP theme-related CSS may be hindering this?