Now before anyone asks, no this is not from the hotbar. This is from inventory directly clicking on the pieces. I have tested 2 DLC T3 Foundations as well as the regular T3 foundations. None of these or relative pieces at T# currently give xp. I am posting here as I could not find a list to add this to for questions and fixes.
I edited this as I have just tested T2 and that is not working as well for experience