I was having a similar issue, but only when parked in our drive. I level it (jacks down) and keep it plugged in and the AC running, but our drive slopes so much the system stops and indicates excessive slope, even though the bubble level on my iPhone shows it's within a degree or two. Last time I parked, I played with the levelers manually after it finished auto leveling and got it just a smudge closer. Voila! It now drains through the lines under the coach!
2015 Legacy SR340 360RB
2014 Jeep Wrangler Unlimited Toad
Gigi, Poppy and Sadie Lady...On the road, but not full time!