I would try a different app just to rule out a Simple Automations Rule bug. Maybe try Basic Rule or even Rule Machine and see if it is any more reliable. Or you might try just Sunset instead of the offset.
It might help if you could pinpoint it to either the app itself, or a sunset scheduling or offset problem.
To add to the above, I'd turn off the "on/off optimization" setting (if you keep this app). That will avoid problems with "missed" commands if the app skips them because the device didn't report back the correct state, which can be a problem for early Z-Wave devices.
Well, that makes sense that optimization would cause this problem. The log shows that the light doesn't really go off when the off event happens (that's the bug), and gets dimmed down a low level. I see various levels 2%, 7%, 9%. When the rule says to turn it on the next day, the optimization sees the light at 2% (i.e. not off) and doesn't turn it on. That night the rule turns it off fully, and the next day it works.
Ok, I'll turn off the optimization, and see how this goes. I probably should turn it off for all my rules, it may be causing similar issues.
I wasn't aware there were different ways to implement a simple timer. If you were trying to automate some lights like I'm doing, which app would you use?