Got up this morning with not much to do, so fiddled around with the three brewvisions I have. One short probe and two long. Short probe was in the keggle I'm trying to sell since I got a new HLT last week. And had a thought; what if I put the short probe in the BK (which is the one I use for BIAB, when I go that route), so one of the longer ones could be installed in the mash tun? Gathered tools, read instructions three times, and got it done! And discovered something that made my eyes roll. I've always measured the temperature of my mash with a stick thermometer at the top; you see where this is going? Turns out the top is about 4 degrees higher than the middle, which means I've probably been mashing about 144-146 for quite some time. Would explain crappy efficiency. It's going to be beer, just not the ABV I was hoping for in a hazy NEIPA. Oh well, I do like learning!