In v13.7, using the Group Member Add from Attribute action does not have an option for Group Member Status that you're adding. To change or set the group member status you will have to do another action Group Member Set Status after the Group Member Add from Attribute.
The option for changing status when adding a group member is only available in Group Member Add action. I wonder why can't it be added in Group Member Add from Attribute action as well?
Anyhow, I think the Group Member Status is related to how the Group Member Workflows is being triggered. I added a Group Member Workflows and I set:
When: Member Added to GroupWith Status of: PendingWith Role of: Member
I am adding a group member via workflow using Group Add Member from Attribute action then I want the status to be Pending so I add a Group Member Set Status action right after adding a group member. That Group Member Workflow is not triggered at all unless I change the With Status of value to Any or Active. My guess is the workflow trigger only checks for Active Status (which is the default status) or No Status is set (for Any). So I thought, it could be the Status is not set to pending when the group add member from attribute action was run so the pending workflow was not triggered.