Peppy Player Headphone output not working

Hmm, I have a different result. It works without any errors. Though I ran collector on Windows machine using Python 3.7.4 and mutagen 1.45.1.
I created folder with one my file and yours. Then ran the following commands:

Bash:
>python collector.py create -i c:\music\mutagen-test -o c:\collection\test.db
[2023-05-30 14:53:15,158] {collector.py:141} DEBUG - Connected to the collection database c:\collection\test.db
[2023-05-30 14:53:15,158] {collector.py:143} DEBUG - Collection tables don't exist
[2023-05-30 14:53:15,374] {collector.py:146} DEBUG - Created collection tables
[2023-05-30 14:53:15,374] {collector.py:761} DEBUG - Counting folders in c:\music\mutagen-test

[2023-05-30 14:53:15,390] {collector.py:772} DEBUG - Found 1 folders
[2023-05-30 14:53:15,390] {collector.py:773} DEBUG - Time spent (h:mm:ss): 0:00:00.007999
[2023-05-30 14:53:15,390] {collector.py:141} DEBUG - Connected to the collection database c:\collection\test.db
[2023-05-30 14:53:15,390] {collector.py:526} DEBUG - Creating collection
Progress: |██████████████████████████████████████████████████| 100.00% Complete
[2023-05-30 14:53:15,606] {collector.py:528} DEBUG - Collection created
[2023-05-30 14:53:15,606] {collector.py:491} DEBUG - Creating summary...
[2023-05-30 14:53:15,606] {collector.py:122} DEBUG - Collection database c:\collection\test.db exists
[2023-05-30 14:53:15,691] {collector.py:507} DEBUG - Summary created
[2023-05-30 14:53:15,691] {collector.py:530} DEBUG - Creation process completed
[2023-05-30 14:53:15,707] {collector.py:681} DEBUG -

******************* Metadata Statistics *******************

Scanned folders:  1
Total audio files:  2
Parsing time (h:mm:ss):  0:00:00.112889
Errors:  0

************************************************************

To verify the data in DB I executed the following commands: open DB and list data in the 'metadata' table:

Code:
>sqlite3 c:\collection\test.db
SQLite version 3.30.1 2019-10-10 20:19:45
Enter ".help" for usage hints.
sqlite> select * from metadata;
1|\|example.m4a|m4a||Example Files||||M4A Test File||44100|2|16|36.6461224489796|195790
2|\|test-mutagen.m4a|m4a|Classical|The Four Seasons|Antonio Vivaldi|Christopher Hirons, Christopher Hogwood, Academy of Ancient Music & Nigel North|Academy of Ancient Music & Christopher Hogwood|Violin Concerto, Op. 8, No. 1, RV 269 "Spring": I. Allegro|1984-04-02T08:00:00Z|44100|2|16|209.165351473923|256000

It showed both files. So, I'm not sure either 'mutagen' has some issues on Mac or different version of Python/mutagen has impact.

Best regards
 
You really have two files in that folder. To double check just run the command 'ls -la' in that directory. It will show you normal file and a "hidden" file which name starts from dot '.'. You sent me the file without dot. More likely that hidden file has the issue. I'm not sure who creates that hidden file. Probably you have some process on your Mac which does that for iTunes files.