[BB_TX]

Also look under the kitchen sink. And someone posted they found theirs behind the convenience center, but I don’t remember the floorplan. Another possibility would be in the wall behind the shower. If you can see under the shower and see 4 pipes going up where you would expect to see only 2 (hot and cold) then that is likely it. But a failed flush anti siphon valve normally leaks rather than blocks flow.