Importing MP4 video file - only audio works and transfers to sequence (no video)

Hi,

Having a few issues with Premiere Pro and would appreciate all advice!

Only audio is available after importing a video file to the project window.

Video is not available or can be seen when transferred to the sequence window.

Even the blue video icon disappears in the small video box in the project window.

I have looked through similar posts.

- I have cleared the media cache. ( I am only starting on Premiere so it would be empty)

- I have updated my macbook to latest software

- I have restarted the macbook

- I have renamed the files to remove 'MP4' but this didnt help

Thanks

Evelyn