Nothing in what you have done changes my mind.
It is the way you are allocating the space for your forum that is causing the problem. You need to learn how to get Wix to allow you to have content that expands as required. At the moment you are setting a particular height for the "box" in which you place your forum. You need help at Wix for that. It is NOT a Nabble problem.
Volunteer Helper - but recommending that users move off the platform!
Once the admin for GregHelp now deleted.