Hello,
I set Zotero to rename my attached file with this custom pattern
{{ year suffix=" - " }}{{ firstCreator suffix=" - " }}{{ title truncate="50" }}

If I'm on my personal library it works fine
https://s3.amazonaws.com/zotero.org/images/forums/u881038/9sh5h5d4toa14mwmfdz3.png
and the attached files are renamed properly.

If I do the same on a group library it fails :
https://s3.amazonaws.com/zotero.org/images/forums/u881038/1n7blzzre7993ug9ad6t.png
And the attached files are renamed using the default pattern.
If I "touch" my custom pattern, it changes the example but still does not rename the files accordingly to my custom pattern :
https://s3.amazonaws.com/zotero.org/images/forums/u881038/pou03tb79398yduremef.png

All group members can modify my group library :
https://s3.amazonaws.com/zotero.org/images/forums/u881038/mokqc4m508dzwfojc7ov.png

Am I wrong or is there a bug somewhere ?

Thanks, regards :-)