I was patching some clusters this week that was newly deployed before Christmas for a client where two of 4 nodes where showing Update readiness Critical.
Running the different commands to try and figure out what was happening we where getting a Access Denied error.
You can see this by running the following powershell command
Get-AzsSupportEceData
Then Run this command and pipe in the ID number in the first row wich for this example is what is marked in white.
Get-AzSupportEceUpdateDetails
If you get this error it means that the LCM Domain Account user that you created, that it’s credentials is not in the ECE store anymore and it can’t connect to the nodes to start checking it’s things.
This is also a known issue and can be resolved by following this guide.