.mp4 doesn't render

Importing an .mp4 file with a .h264 codec.
Assigning it to a Media Player, but the .mp4 video just shows a blank image.

It works fine with an image sequence. But .mp4 just doesn’t render the image.

Windows Pro 11, 64bit.
I am also using the latest Adobe Media Encoder packages.

The .mp4 videos run great outside of UE5. But once imported and using the media player, the canvas stays blank.

Thanks for any ideas or thoughts,
appreciate it!