When you put gas in it are you filing it up to it stops and then topping it off even more???
I would try to only put max 3/4 tank full and see if it helps, could be a combination of over filling the tank and the fuel expanding putting a tad bit to much pressure on the EVAP system and purging it out… And possible a rubber O-ring not able to hold the EVAP pressure enough to keep the fumes from leaking but not the liquid… But if gas is leaking anywhere it should be leaving a visible trail even if not hitting the ground…