Well, the tracker button is only movable if some addon makes it movable, so I would say your question shouldn't be "what addon is preventing the button from moving?", but "do I have any addons that are making it movable, and if yes, why aren't they doing so?".
I have one - DetachedMiniButtons. When all my addons are enabled, I can move all buttons, except my tracker button. But when I disable all addons except SimpleMiniMap and DetachedMiniButton, I can move all non-hidden buttons free.
Well, I don't see any addons on your list that should be preventing those addons from moving the tracking button. If you move it with only those two enabled, and then enable the rest of your addons, does it stay where you put it? If so, you might just want to do that. If not, or if you really want to find out which addon is causing the problem, you'll have to enable your other addons on at a time until the problem reappears; when it does, the last addon you enabled is the culprit.