Hi!
Thank you for all the details. It indeed does not work, it looks like my previous solution does not work after all. The problem is, that I don’t know what else to try – it would probably take long hours to study their code and somehow get the proper function to integrate with this.
I have tried a few different solutions, but none of them seem to work. Can you please ask their developer, what is the proper way of checking programatically, if the current user has access to a given post by the post ID?