MP4 video not displaying/rendering?

On Windows 10 with latest version of Race Render 3, I can add Mp4 files in hevc, but only the audio seems to play in the editor and is the only thing that renders on output. Have played with a few codec packs and confirm they are working in Windows Media Player (Microsoft prompts for purchase when not installed and video plays through fine when installed). Have tried re-installing Race Render to pick up the codecs to no avail. Kind of at a loss at this point; seem to be passed the basic RR troubleshooting guide.