I am guessing the issue is actually with those Leviton Z-Wave switches/dimmers. There is a known issue with Leviton devices NOT reporting there status updates back to the hub. To fix this issue, a firmware upgrade on the Leviton switches is necessary.
There are numerous threads regarding these Leviton switches. A simple search turned up this one which seems to have quite a bit on information in it regarding how to upgrade the switches.
