I first found this:
which focused on a TypeScript related problem and didnt help my issue.
I have ReSharper installed, enabling the settings below solved my issue:
To toggle ReSharper syntax highlighting Open the Code Inspection | Settings page of ReSharper options. Use the Color Identifiers check box to enable or disable ReSharper syntax highlighting. Click Save to apply the modifications and let ReSharper choose where to save them, or save the modifications to a specific settings layer using the Save To drop-down list. For more information, see managing and sharing resharper settings.