Hi Vero,
First image was the security settings after the update to the latest version of Alfred. Second image shows the security settings and the workflow working under v3.7.1.
I've just updated to the latest pre-release build again and the workflow is working again as normal. While it has resolved my issue, I'm not sure if that helps you debug what happened the first time I upgraded.
If I can gather any other info, just let me know.