Many thanks. For me I had no add-ons installed.
I have solved it now. If you start on the Runway the first time you use a plane it then it works after. I was trying to load the new 2024 version of the Just Flight RJ before all this started, It would not load, then nothing would load. I uninstalled everything and started again.
I then read the FAQ on the just flight forum, which I had missed, and they said to start on the runway on the first load of the plane as it makes sure it all initialises. So I did this with the A400M and the 330/321/320V2 and boom they all loaded. Then I reloaded but at the gate and it all worked.
So it seems and especially with Add-on planes on first load, start on a runway.
In any case many thanks for being helpful, unlike the guy above throwing out silly comments and his crystal ball where knows how fast and “Cheap” my internet is. Thanks.