We are experiencing sporadic issues with `@RenderComponentField()` in our Razor templates. It seems that sometimes it does not render the field, just an empty TCDL tag, even when there is content in the field. 

I have not yet managed work out any pattern for when this is occurring, initially we thought it was just embedded schema fields, but now it's happening on the most basic top-level text fields. For example:

<!-- language: lang-razor -->

    @RenderComponentField("Heading",0)

Changing the code to 'normal' syntax it works fine with the same content:

<!-- language: lang-razor -->

    @Fields.Heading

Has anyone else experienced this, or have any idea what might be going on?