So, as I remember, you are the person who helped me when I transferred my library. Everything had been in iTunes on my prior iMac. I brought the data over to my MacBook Pro and then created a TV Library. I also had to change the setting to keep organized and reset the location as you had instructed.
Everything else was left as it was. Most files ended up where they should have, but some did not. I have only used the Finder to locate where the missing files are, because the apps do not know where they are. They do not show up in the TV or Music user interface. And I cannot import the .mp4 files.
When I look for these files I find that many, if not all of them, are in a Music media library that is different from the one that I created with the data now on my external SSD connected to my MacBook Pro and, of course, different from the TV Library that I created at the same time.
The data on the external SSD looks just like it did before, e.i. it looks like it did when I was using iTunes: Music>iTunes>iTunes Music>Home Videos, Movies, Music, TV Shows.
Within the TV Shows folder there is a Show folder which should contain 6 seasons with over 300 videos. It did include that when I completed the transfer, but only season 6 showed up in the TV user interface.
Now it mysteriously shows folders for only seasons 1, 5, & 6. Season 1 contains 69 video files none of which appear in the TV user interface, Season 5 contains only 1 video file which is not in the user interface, and Season 6 contains 23 video files all of which are in the user interface. Some of these 23 videos were created before I had my new MacBook, so they were transferred correctly and added to the TV app and some were created later in the TV app.