Can't browse or insert images into pop up

Hey guys, something is amiss with the pop-up admin interface.

For some reason I cannot browse my media / image library to insert image into pop up message or select hero image for the pop up, even on an existing pop up campaign.

Everything else works perfectly.

Desperately need some assistance on this as I am launching a big campaign today and would like the pop up to align with eDM.

Cheers... Brett