MY HOME>THINGS Leviton button stopped working, commands work fine

I have 4 z-wave leviton light switches. in smartthings droid app MY HOME>THINGS tab, all 4 lights originally turned ON and OFF no problem.
Now, 2 of the lights will not change state in the THINGS tab. On & off core commands work fine on these lights. I tried to exclude and include a switch, but no joy. I could not find a thread on this issue.

What model switch do you have?

Leviton DZ15S-1BZ decora z-wave switch

FYI, 2 of the 4 continue to work normal. 2 specific switches control no prob via core, just not in things tab.