At this point I would state that if you ever have problems with other appliances/electronics around the house it would be time for a serious look at your electrical system. Maybe just tightening ground and neutral connections. Possibly look into some disturbance protection on your electrical system. Make sure your cable TV, phone, or any other conductive incoming line into your house (used or not)  is all connected to one good grounding location, You don;t want lightning disturbances looking for a place to go somewhere, go through your equipment.

Edited July 14, 20178 yr by larryllix

Thanks guys. The house seems solid from an electrical perspective. Rarely, I may have an RF device need a soft reset but this is the first time anything of this magnitude has happened. Loss of communications with these few RF devices is not my primary concern. What I am concerned with is that the ISY opened with the Admin Console, displayed several small windows saying it could not communicate with several devices  and "froze"—I could do nothing. On the other hand, ModiLinc showed those devices as unaccessible but continued to work as designed. My best guess is that an electrical anomaly, such as a power interruption, caused these events. But note, the first thing I did was a power reset of the ISY and that did not resolve the problem. I had to do a soft reset of every RF device that had failed to communicate before the ISY could be successfully accessed from the Admin Console. That, to me, is both weird and a bit alarming. Why did the ISY freeze because of these RF devices? If anything further of this sort happens I will report back.