I'm using Vegas 11 Ultimate on a Windows 10 machine and I have imported MP4 video files from my phone. When viewing them in trimmer, the audio is good but the screen is black. When dragging them from trimmer to the timeline, only the audio appears on the timeline.

I had Quicktime installed - did not matter.
I uninstalled Quicktime and Windows 10 can still play MP4 in its Media Player but Vegas still renders a black screen.

Can anyone suggest a fix for this?

Thanks!