If you’re having problems with the HA add-on for vscode working check your .vscode/settings.json file in your workspace. You need to update your file associations so that the HA extension is being used instead of the standard yaml exension. They conflict with each other and you have to override the default behavior.
Update the file to
"files.associations": {
"*.yaml": "home-assistant"
},
That will force the HA extension to be used for yaml files. It the default is still in place "*.yaml": "yaml" then the redhat-yaml exention is used and the HA extension is never triggered to load.