2014 16BHB - black tank vent issue?

[Rex]

I have been doing a lot of reading in the achieves. I see all the stories of the 21BH shower draining into the blackwater tank. I saw where they inserted the vent pipe for the tanks lower into the tanks reducing the capacity...

We took our new to us 2013 16BHB out for a maiden voyage this weekend. Just a short 2 night trip, no showers. I noticed that when you flush the toilet it seems to Burb, like the vent line is plugged. Is this a known issue? I would guess that it could be the vent pipe inserted into the tank, but since it happened early on, the pipe would have to have be toward the bottom of the tank.

Is there some known issue, or some common culprit?

[Rex]

We did another trip in the new to us trailer. I monitored through the weekend. At the start it was working fine, but mid day on the 2nd day, it was "burping". I suspect that the vent tube was inserted to far into the tank, so it quickly gets covered and sealed off.

[Merlin]

The black tank vent works a bit differently than the grey tank vent because when you flush the toilet the black tank is open through the toilet. The black tank roof vent does need to be clear to vent the tank when the toilet is closed. The grey tank is sealed all the time except for the roof vent. When does the black tank burp? Right when the toilet is flushed? Any odors inside the camper?