Thanks for the quick reply. I'm still learning about all this stuff so sorry for not providing useful info in advance. I do have repeaters, 3 of them placed strategically to ensure the Z-wave signal reaches everywhere it needs to. Regardless, I seem to have resolved the issue, at least for the moment. I found the hint I needed here: Quick Z-Wave fix
It turns out that turning off the Z-wave radio, waiting a while, and turning it on again seems to have reset everything to working again. I don't know why it stopped working in the first place. Maybe something got clogged up in there? I'm still having a little trouble with some Zigbee contact sensors but I'll work on those tomorrow. I think the radio reset might help there also.
