Audit log not working for Cases Module

Hi there,

I'm facing a strange issue on our customer's instance. 

The audit log is not working for the Cases module. 

I tried to debug the API, but the code doesn't pass within the function viewChangeLog located in modules/Audit/clients/base/api/AuditApi.php.

This behaviour only happens for the Cases module.

I have also another strange thing that is the cases could not be exported from the List View, I'm getting an error in the developer console "No valid login for the user".

Did you ever face this kind of issue ?

Thanks in advance for your help and feedbacks.

Best regards,

Enes