Z-stick not recognizing new devices

I’ve been using HA for about a year with no real issues and this is my first time posting.

Recently I’m having some issues with zwave network. I’ve read up on possible issues and I can’t place it. I’m at a loss and would be grateful for some advice before resorting to excluding all the devices and factory resetting the zstick.

I think there is some mismatch between the zstick config and HA/ozw. I’d like to be able to solve this without starting back and re-building the zwave network node by node. Dreading this idea with less than 20 devices, can’t imagine how people with 50-100 devices would deal with this.

My setup: Home assistant 0.93.1 running on a Raspberry Pi 3 with Aeotec zstick Gen 5.

Background on the issue:
I had 6 zwave device functioning on the network for a long time. I tried adding a few additional devices one at a time, got an Aeotec working then added a Popp radiator valve. The valve was not recognised and came up as an unknown device. I tried removing from the network without success, then a factory reset of the valve device and removing the node in HA Zwave Management. I rolled back HA to a previous backup. The bulb was no longer part of the network but the unknown node remained and cannot be removed.

I now cannot add any new devices. The zstick happily includes the new devices but they do not show up in HA zwave Management.

More details on the Nodes currently:
There is 1 unknown node in the zwave Management menu (Node 14).

The HA error log shows 2 unknown nodes not responding (Node 14 & Node 15): ‘Z-Wave entity Unknown Node 15 Level (node_id: 15) not ready after 30 seconds, continuing anyway
**9:08 PM components/zwave/init.py (WARNING)*’

The zwcg.xml shows:
Nodes 1-8: full details of the working nodes.
Nodes 12, 13, 14: a couple of basic details like ‘type’ but no device name or anything I can identify with.
Nodes 9, 10, 11: no entries at all, though I think these were previously unknown nodes when I’ve tried adding devices since the issue began.
Node 6: disappeared somewhere along the way a while ago, I understand this is not uncommon.

Many thanks in advance for any advice!

In case this helps anyone in the future:
Think I solved this after reading the zwave instruction pages more thoroughly about “Removing Devices”. The unknown/unresponsive nodes can be removed manually by setting their failed state to true: {"node_id":6, "is_failed":true}.

I did this for unknown node 13, restarted HA. Unknown node 14 then came up in the zwave device list, removed this the same way, restarted HA. Unknown node 15 then came up in the list. After that I was able to successfully add new devices again.