Yeah, that is the exact kind of flavor I'm getting.
Sounds like we're in this together.
I'll tell you a little bit about my setup, and what I was doing, and what Yooper has since suggested I try.
Before:
I do 1 gallon all grain BIAB. I use a 3 gallon kettle and add my full volume of (Poland Spring water) to the kettle (accounting for boil off/grain absorbtion/etc). I add all of my grains and mash for 1 hour. After 1 hour, I stir my grains constantly until I achieve 170. I then cover my kettle and let it sit (with the heat off) for 10 minutes. After 10 minutes, I pull the bag out, squeeze out all of the wort from the grain, and then start my boil.
After
After having the same flavor on ALL of my beers (mostly in my IPA's, but definitely noticeable in all of my beers), Yooper advised that it's most likely my water, or the fact that I'm using such a small amount of grain (approx 2-2.5 lbs in about 2 gallons or so of water). She recommended that I move to either RO or distilled water, and add some calcium chloride to the total volume of water that I plan to use. Further, she recommended that I pull out some of my water and put it in another (smaller) kettle. This would allow for my mash to be a little thicker (less water per that amount of grain). After going through my normal process as outlined above, I then pull the grain bag out, squeeze, and then dunk it in the other kettle, which I heated to 165 (down from 170 in my prior process). I dunk and rinse the grains in this water, trying to extract all of the remaining sugars. Then, I simply dump that water into my brew kettle and start the boil.
This update to my process has hopefully eliminated the pH issues I've been having, however, the beers I've tried this with are still about 2 weeks away from being tasted/tested, as they're still conditioning.
I'm curious to hear your process, as it sounds like we have the same issues...I'm just assuming yours are on a a larger scale since I only do 1-gallon batches.