So, all my own fault in the end it's looking like. The opportunity came up in work for some industrial temperature calibrations so I got to check and it turns out my 'calibrated' thermometer I bought was a good way off. I've done the Brewzilla with the adjustments since (only calibrated the high and low between 60 and 76 using this information) and I've seen 84% with LAX and 77% with Hoppin Pils since.