www.makemkv.com

This is so simple, it either can't be done or I'm missing something obvious.
How do I open M2TS file so I can convert it?
When I navigate the "Select exsisting video source file" window to the "BDMV/STREAM" folder, all I see is "No items match your search".
As you can see from the screenshot, the background shows the same path, and file 0010.m2ts is clearly there.

https://photos.app.goo.gl/LspPU4VN0Nh8LIMQ2

Background:
I have ripped my BD collection some years ago.
At that time, I ripped it using original settings, file format, etc.
It's been playing just fine using any number of players.
Even if the file was corrupted or ripped with wrong software, it would still show up while searching for it and perhaps error out when trying to convert. I get nothing.

Recently as my server filled up, I wanted to reduce the file size and figured that MP4 or MKV conversion was the easiest way.

MakeMKV doesn't look for m2ts files directly; if you look at what is listed in the pull-down of file types, "m2ts" and "mpls" are not among the types searched for.

If the disk has already been ripped and decrypted, you could open the m2ts and the play lists with something like mkvtoolnix tools or Handbrake directly.

If you want MakeMKV to open them, you would open the backup itself, by opening the index.bdmv file found in the backup's BDMV directory. It will be among the few files visible when you navigate to that directory, and opening it will find the titles by reading the playlists.