What is ITSM/SRM version?
In the filter logs do you the filter SRM:REQ:Notify_Approver working?
We are using ITSM 8.1/SRM 8.1 version.
No filter SRM:REQ:Notify_Approver is not working.
I am experiencing the same issue, was this ever resolved? I am on 9.1
Is it a custom approval process?
If so, can you go to AP:Administration form and select the process.
Navigate to Notification tab and check if you see any entry?
If not then create one for New Signature by making use of any OOTB approval process.
This was exactly my issue, thank you Harshad