It seems like there might be some errors slipping through the cracks for you. Have you checked the TypeScript preferences in your project properties to ensure that TSlint validation is enabled when tslint.json is present? This setting is specific to each project and not applied globally across the workspace.
If adjusting this setting doesn't solve the issue, could you provide an example of an error that isn't getting flagged? Or are the errors not appearing as expected in the Markers or Problems view? It might also be worth creating a new workspace and starting a fresh Angular project (or another project with TypeScript files) to rule out any possible corruption in your current settings.