Using Start and Stop Time

[CRMS]

Not sure is this is a Windows issue or a general issue.
I'm using VLC 3.0.12 on Windows 10 - 21H1.
I am trying to extract the audio from a .ts file, recorded off Freesat radio on a Freesat recorder so no video anyway, and convert/save as .flac.
I also want to trim 5 mins off the start and 30 mins off the end.
So I've selected "Show more options" and entered the start and stop times, which are reflected in the edit options as seconds.
But after selecting Convert/Save, entering a new file name, and Start, the whole .ts file is converted to .flac.
Just wondered what I am missing??