I am unable to help you as I do not have TacPack, and the current version of Draken is neither prepared for nor tested with TacPack. My guess is that TP overrides the fuel tank selector through SimConnect to be able to implement in-air refueling, etc. I would have to go through the TacPack SDK first to figure this out.
There will eventually be support for TacPack in Draken but I have been up to my neck in work so this is still on the “waiting list”.