Hi Marinus,
Thank you for reaching out, I’m sorry to hear you’re experiencing this issue after updating BoldGrid Post and Page Builder for WordPress.
I have a theory, as a test can you temporarily disable the Popup Maker plugin you use for your initial verification. I think something in the JavaScript is causing the page not to load properly.
I also suggest refreshing your permalinks and clearing any cache you have associated with your website (including browser cache and any server side caching agents).
I hope this helps. We’re here to answer all your questions so don’t hesitate to reach back out.