Thanks very much for moving on this so quickly, unfortunately I am still getting the same error.
I have added a PID using your variable, it downloads the video file successfully, converts to MPEG-TS, then when trying to convert to MP4 it throws the same atomic parsley error.
2023-10-02 15:58:43,889 DEBG 'get-iplayer' stdout output:
INFO: Converting to MP4
2023-10-02 15:59:05,738 DEBG 'get-iplayer' stdout output:
WARNING: Required AtomicParsley utility not found - cannot tag MP4 file.
I have tried forcing update and fully removing and re-installing via CA.