Been using the backpack and this item retriever now for few weeks and I've noticed that the Retrieve Toggle needs to be turned off, then back on in order for it to re-active when reconnecting to server. Otherwise it will not retrieve to reload guns from ammo stored in backpack, or use resources or craft with backpack items. Toggling it OFF then ON again fixes the issue, but maybe you could add some sort of IF then else statement to handle based on players defined settings?
This way it checks if player has ON or OFF first. Then... If Toggle = 1 (on), utilize some sort of auto re-establish or auto toggle OFF then ON again in the background. If Toggle = 0 (off) then do nothing as the player has opted not to use or hasn't configured. 

you aware of this issue?

I replied to your original post in the Backpacks forum. The symptoms you described appear to be due to a combination of "lazy" loading (a performance optimization in Backpacks), and stale inventory snapshots (an issue which can be easily fixed in Backpacks).

ok thanks, appreciate the response. Keep up the good work :)