cookie pop-up banner always disappearing in split-second?

hey lovely people (:
I have a problem with the cookie pop-up banners in my shop - they appear for a split-second and then disappear before you've had the chance to read or accept them. Deleting cookies in my browser doesn't help and choosing the different options of banner or pop-up does not help either. I'm not very well versed with pop-up and cookie stuff, so I'm not sure what to check next and I need them to work properly.
Have any of you run into that problem and/or know how to fix this?