I have a similar issue too. My display is a Mitsubishi WD-82738. When the Display 3 is set to "Standard," it takes a long time to take readings; when set to "Plasma," it reads super fast.
However, on both settings, 40 IRE has issues. It takes forever to read and the results are very inconsistent. Like your issue, I'll have a few good readings and then a couple off the charts.
However, on both settings, 40 IRE has issues. It takes forever to read and the results are very inconsistent. Like your issue, I'll have a few good readings and then a couple off the charts.