Issue with adding multiple component leads to user picker custom field

Unable to add two different component leads to a multiple user picker custom field in a post function(Create Sub-task). After issue transition, both component leads are not getting assigned to the custom field.

For example see the below:
%function_componentLead(Project1, Component1)%, %function_componentLead(Project2, Component2)%

Steps to reproduce:
1. Create Sub-task post function.
2. Create a multi user picker custom field.
3. Add %function_componentLead(Project1,Component1)%, %function_componentLead(Project2, Component2)% to the above custom field.
4. Save the post function.
5. Do the workflow transition.
6. Check the sub-task's multi user picker custom field. It is not picking up both of the Component Lead values to the field.