Water pressure sensor leaking

I am using the Seeed water pressure sensor (SKU 114991178) in an espresso machine to measure water pressure. Unfortunately, the sensor is leaking! I connected the sensor’s G1/4 male connection (same as BSPP 1/4") to a BSPP 1/4" female with teflon tape on the threads and it leaked. I added more teflon tape and it still leaked.

Attempt #2: adding an o-ring to the sensor. This also leaked. I think the sensor should have a gland or receiving surface for the o-ring, but it does not.

Seeed engineers – how do you get a good seal with this sensor?

I’m really sorry, we’re going through the Labor Day holiday, and on May 6, I’ll be consulting the supplier of this sensor for advice on preventing water leaks. @nojkceb