They did say that the "fix" was to elevate the drain.Did they indicate what was being fixed with the repair kit?
I don’t think the water leak is from the gray tank vent, there is probably a leak in the gray tank plumbing. Have them check that out when you drop the RV for repair. I could not imagine RT adding a gray tank vent under your rig, if they do, that would be bad as gray tank fumes could creep up inside the van, not to mention gray tank contents leakage into the ground when tank gets full. Holding tank vents are usually vented into the roof.They did say that the "fix" was to elevate the drain.
I believe they meant elevate the VENT.........
because when experiencing the problem I discovered that although the grey tank was almost empty, an amount of water came out the vent while I was trying to force the water down the shower drain.
This led to my idea that the angle of the Agile was causing water to block the vent, so I repositioned the Agile so the front was slightly ( and I do mean slightly) higher than the back.
The standing water in the shower drained immediately, which indicated to me that where the water had leaked near the front of the tank was where a vent was located and the theory of blocked vent may have been correct. On our forthcoming trip, I am taking a length of flex. tubing and if the drain plugs, will insert the tubing into the drain to introduce air into the system.
A dealer has ordered the repair kit for me and will install it on our return.