In a few cases I also got the next_page_token but on using that I got an error saying the next_page_token is invalid. In any cases I was not able to get back the meetings for the files present in trash.
In taking a closer look at the user in question, I’m seeing that they don’t currently have any recordings in the trash. I see that they have 214 recordings in cloud storage, but none in the trash, which I believe is why you’re seeing this array to be empty.
However, let me know if you’re seeing otherwise from your end when checking that user’s recordings via the UI.