Can you list the details of the three instances of Home Assistant?
As I understand it, all three are installed as Python virtual environments.
One has just four z-wave devices.
All use the same brand/model of z-wave controller.
How may devices on the other two instances?
Which ones have dead nodes?
etc
All use V5 of the Aeon Z-Stick on Python virtual environments, yeah.
System 1 (main system) on Pi 4 with Buster, clean install a wek ago, Home Assistant 0.96.0: 15 devices, with the mentioned Telldus switches, Heat It! thermostats and one ID-lock. Of those one switch is dead (pulled for testing purposes, but plugging it doesnāt change anything), and the ID Lock is dead (because of an error in the lock itself, not the Z-Wave system board or other system).
System 2 (runing control system that switches off and on power to four other Piās), Pi 3B+ with Stretch, clean install this winter, Home Assistant 0.91.4: Four of the Telldus switches, nothing else. Nothing dead, all good time.
System 3 (cabin system) Pi 3B or 3B+ (not sure, and Iām not there now) with Stretch, installed last summer and upgraded along the way, home Assistgant 0.91.4: 5 devices, with two of the Telldus switches (one dead, only because itās not used at the moment), one internal AN179 In wall ON/OFF Module, one ID Lock and one Heat It! thermostat.
Interesting.
None of these three instances is producing a network_ready event and two of them are using 0.91.4. That means the lack of a network_ready event is not something due to recent changes (if any) but dates back to at least 0.91.4 .
Both you and finity are using the same z-wave controller brand and model yet his system produces a network-ready event but none of yours do.
The presence or absence of a dead-node appears to have no influence on the production of a network_ready event.
Puzzling clues. There must be some critical differentiator between your three systems and his. 
I think we determined the only real difference is that Iām running in Docker.
I donāt see how that could make any difference but there has to be something and thatās the only glaring difference.
It could be (and likely is) something else but thatās the best info we have for now.
I will install a new Buster setup for the simplest network (running control system) and only move the Z-Stick, none of the configuration files, and see what happens. May take a few days to get around to, though.
@finity Final thought: Do you do secure inclusion of everything? I only do secure inclusion of the door lock, I figured the rest isnāt as critical (and besides nobody does Z-Wave around here, itās not the most automation heavy neighbourhood).
If the device supports secure inclusion I include it that way. I figure itās there for a reason and itās just as easy to include it securely as not so why not.
OK, then we have another difference. One of my reasons for not doing that is that I could bring the Z-Stick around to the different thermostats in the wall and include them by pressing the button on the stick. But can that be the reason? Am I the only one not doing secure inclusions of everything?
And thereās another difference, too.
When I first started using HA two years ago I included my first couple of devices by using the button on the stick.
then I read somewhere that the āpreferredā way was to use the zwave control panel in HA to do the inclusions. Now that has transformed into the ārequiredā way is to use the control panel and never use the button on the stick. I donāt know of any explanation of why that is the requirement tho.
Iām not sure why or even if that could be the cause of any of the issues you are having but itās another point of information.
Come to think of it I have not included the ones in the cabin or the keep alive network in any other way, thatās been done either from OZW control panel (the cabin, that network started when I was still using Node-RED for Z-Wave, and that needed to use OZW Control Panel to include) or directly from Hass (the keep alive network). Only not secure.
Edit: The manual for the switch doesnāt mention anything about secure inclusion, that may mean that it doesnāt support it anyway.