The code you’ve provided is what runs the checks for the permission, and does not set the permission; that’s not going to help us in order to pinpoint the issue you’re facing If the check is returning true and running well in Preview, then its most likely that you haven’t ‘set’ the permission right.
I’m linking a forum post below where another user wanted to achieve something very similar to what you are trying to do, so I’ll refer you to my solution, which works as expected; and I’ll recommend you go through the entire thread from the beginning and if needed, try building out this functionality on a new test site first, and once you get that right - implement it in your current site.