Exported file has black screen segment

Hi, I am new to HitFilm. I'm trying to compile/combine multiple videos of different formats (MP4, MOV, into a single video file (MP4 format).

After exporting, the segment of the MOV file turns black screen but there is audio for this part; the rest of the other segments looks and sounds good though.

Need help to fix this issue.

In the editor, the MOV file also shows a yellow warning exclamation on it, and a message "The video frame cannot be displayed" in the Trimmer.

The MOV file plays just fine on VLC or Windows Media Player.