Plex Server won't recognize m4v videos when adding to library

Plex Media Server Metadata & Adding Files
1

Server Version#: 1.15.4.994
Player Version#:
I have added videos in M4V File (.m4v) that can be played with the Windows 10 Movies & TV application but the Plex server will not recognize them when adding them to the folder. Can you please assist? this is the first time using Plex as I’m trying to find a solution for a media server in my home.

2

Start here https://support.plex.tv/articles/201543057-why-is-some-of-my-content-not-found/