Custom pick slip ESS process is getting triggered when the shipment lines are pick released

Summary:

Custom pick slip ESS process is getting triggered when the pick wave is created but not when the shipment line is released from 'Manage Shipment Lines'
The user would group the shipment lines manually and performs the pick release process . This should auto trigger the Custom report but instead the seeded report is getting printed.

Note: The Custom document set is added to the Release Rule and it is working fine in case of running a Pick Wave

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):