There are a number of threads related to this issue on this forum. Some users have resolved the issue by simple restarts of HA or reboots of the hardware but my issue still remains.
If I create an automation it gets written to the automations.yaml but does not display in the GUI.
Initially I had duplicate entries in the automations.yaml file as I assumed the first automation did not save. However I have since edited the autimations.yaml file but the automation still does not display. I even pasted the text into YAMLlint but the format passed ok.
I have restated HA and rebooted the NUC but the issue remains.
Any suggestions where I should look further?
OK scrub that. The automations are now displaying 
What I did originally was to create an automation directly from the automations tab.
What I subsequently did was to create a new test automation from the device properties menu instead.
As soon as I did, both the test and original automation are now showing in the automations tab.
I am not sure if this is a bug or if all automations must be created from the device properties.
Automation YAML - Home Assistant.
Note that the HA automations page says:
The UI will write your automations to automations.yaml . This file is managed by the UI and should not be edited manually.
Thanks @bob.t . Under normal circumstances I would agree however I had duplicates in the automations.yaml file and I thought this was what was causing the automations not to display in the UI. As I couldn’t edit the automations through the UI the only option was to remove the duplication from the .yaml file directly.
As it happens this was not the problem and whatever I tried to resolve the issue did not fix it.
However I found that I could create an automation directly from the device rather than in the automations tab. When I did this, the new automation appeared in the UI as did the previously hidden one.
I cant explain why