I can tell you that this behaviour is normal.
If you interested to go deeper into Z-Wave, I recommend having a look into the SiLabs docs.
Now for my testing:
I created a rule that is supposed to trigger my living-room TRVs at once.
Installed the drivers, rebooted the hub.
The result was always the same, 2 out 3 TRVs worked, one failed, without witing any logs.
Also, this very device could not be controlled by any means, entering the setpoint manually didn't work as well refreshing it.
Tried all that several times.
Reverting to your "standard" drivers fixed the problem. Weird.
Edit: I just rembered also having had an issue with long response times, and all of them had been SS7 included with S2-security. Look here.
