The first three add-ons on your list can modify the stock Canaveral/KSC. Set up an install without those add-ons, and ensure the pad is there. Then add the add-ons one at a time until you find which one causes the problem.
If I'm not mistaken, Shuttlefleet 4.5 doesn't use the "stock" launchpads, but uses an "active" launchpad with animations. This is actually a vessel (as far as Orbiter is concerned) and needs to be included in the scenario file. Check the scenarios included with SF 4.5 to see where they should be located, you should be able to cut and paste the relevant lines from a scenario with the "active" pad in the correct location to the scenario you are using.
Also, check the top of the scenario files that come with SF 4.5 to see what "System" they use - IIRC it's not the standard "Sol" system, and you may need to change that as well.