Have you set it up so you are also hearing each track's direct output (in addition to sending it to a submit)? If each track has a different position in the quad field, the precedence effect may be enough to maintain its location, especially if your submix destination reverb has a preDelay. In that case, it would be enough to send all the tracks to the same submix and one copy of the reverb — because often, in a physical space, we can identify sound source locations from their initial transients, and the reverberation is more dispersed. If you use EuVerb, there is also a control on the pan position and delay time of the reverberated output.
When you use Track controls for positioning (angle, radius), and then send that track to a submix, it is the pre-positioned signal that gets routed to the submix (not the positioned signal).