I've been running MPLAB 7.30, and I am beginning to suspect the mode CANNOT be turned off. I discovered I can work around it, though. I already have a question in to Microchip tech support so perhaps I'll get a definitive reply next week.

Meanwhile, I've just downloaded their new V7.40 suite, and as soon as I can get it installed & running I'll be able to checkout the behavior of a brand-new installation!

Thanks, folks, for reading this. This forum is OK!