When you run the hop test? What is it reporting? Here is my test. Which lights are not responding quickly to an on/off command.
Is this a problem with “instant status.” Unfortunately, I have some of the same random instant status problems that you have seen. The problem seems to be more prevalent when a zone command is issued. The zone command causes a large number of notifications. I played around with this some using a zone command, followed by a “group update”. Multiple group updates seemed to produce inconsistent results.
It's possible that you have a weak node somewhere in your network. I would exclude the furthest devices and build a small network containing only 2 hops. You could see if the network's reliability improved. I am trying to track down a Leviton support document that talks about the best practices including using update routes and use a lower power level. This will cause the network reliability to improve, but at the cost of higher latency.
When calling Leviton TS and they cannot diagnose a problem, they just say 24 devices. Nobody has ever proven there is a 24 device limit ... why not 25 devices. I don’t get the feeling that Leviton Support knows how to diagnose random problems. Leviton's own documentation indicates 7500 square feet and 72 devices (RFIT help - Maximize Performance in How Do I…).