Thank you. But the solution does not work. I already have the latest version of Discourse and safe mode doesn’t help.
I understand your position, and I understand that the product is open source. This is one of the reasons I chose it. But what I’m looking for is for some kind of documentation, or points to look for in order to solve the Lightbox issue.
I didn’t know about the Marketplace and I will probably give it a go if I can’t find a solution. But this feels like a free to use app with paid support. Nothing wrong with that, if this would be known from the start 
Either way, thanks for your time. I’ll wait a bit longer.
Maybe there’s other tips from other users about what check in order to solve this.