Old: place pistol mags and any primary magazine/grenade in the same inventory and the pistol magazines will force to top.
Amended: Place primary weapon magazine into inventory, we are unable to have this happen every time, however we are fairly sure this is the cause. We do not currently know why the magazines are being forces to the bottom. But mags being added crashing us and the same magazines forced to the bottom does not seem to be a coincidence. Unsure of what else we can do to test. Thank you for your time.