MKV Extents different for Video Files

I am running into issues when attempting to upload new video files created with MakeMKV. The resulting file extent is different, sometimes EXE, sometimes MKV. MP4 or MOV Files copied directly on to the server drive are fine and do show up in the PLEX app. Where do I start troubleshooting this kind of problem? Any suggestions appreciated.

Running on an iMac (10.15.6) / Catalina

Netgear Gateway C7000v2 (ethernet To TVOS)

TerraMaster NAS F2-210 / TOS: 4.1.24-2005180955

PLEX Server version 4.36.1 / 1.19.4.2935

Apple TV v13.4.6

TIVO Bolt Series 6/v21.9

PLEX on Tivo v3.13.14

Larr2000@Gmail.com

Plex isn’t going to treat a .EXE as a video.

And I’m confused how MakeMKV could create a .EXE.

Usually you only set the output directory in MakeMKV. Even if you set the video name manually, MakeMKV chooses the file name. So I don’t know how you could be doing it by mistake, either.

Can you share a screenshot during the MakeMKV process? That should show the path and filename. When complete, can you show the file that was produced?