Pop Up! / Popover plugin does not activate


I've installed the Pop Up! / Popover plugin and attempted to activate it on a few sites with a contact form shortcode and can't seem to get it working on any site.

A forum thread advised a few tricks but non had any effect.

Please advise how I can troubleshoot.

My plugin settings are below:

Pop Over content: tested Magic Action Box shortcode [magicactionbox id="343"] and plain lorem ipsum text; neither appears

Condition: user not logged in (using sandboxed browsers and machines to test)

Appearance: checked "use Javascript to resize and center the popover"

Pop Over style: Dark Background Fixed; background does not turn dark

Show Pop Over: immediately