Email template sender merge fields

I have an Email template created which I later use in a flow as an Email Action (not an Email Alert). The template uses the merge fields {{{Sender.FirstName}}} {{{Sender.LastName}}}.

However, I am not sure how SF is defining who the sender of the email is because in the flow I am sending this email to a lead that is always assigned to USER A. The flow is created by USER B.

The email action settings are defined so that the "Sender Email Address" is the owner of the lead (his mail is assigned as an organization wide address).

The name of the sender is coming in okay on the email sent, but the merge field from the Email template are not.

The merge fields is picking up the first name and the user that created the lead and the flow (this is an admin user and the lead creation is with a third party integration).

Can this be modified or fixed so that {{{Sender.FirstName}}} {{{Sender.LastName}}} pickup the name of the lead owner? Thank you!

#Flow  #Email Template  #Mail Merge Field