When they added the door, they may not have maintained a continuous downward slope on the vent lines when they jogged them around the doorway. They could be either plugged with debris or water or even just capped. Without proper vents, the traps could end up siphoned. An AAV can't be the only vent...there must be a functioning atmospheric vent in the system...and yours could be plugged. When you can smell the gasses, check the traps. Run some water above if you can, if you can easily hear the water running when you get close to the drains, the trap is likely dry. Run some water slowly and see what happens.