node assignment on re-entry into interface node

I'm on 18.1 and have a situation whereby I am using a receive message to re-enter a process in order to amend details. The assignment for the first interface node is set to a user based on an expression. This is happening correctly however the node is also getting assigned to the original assignee (from the first time this node was processed). I've been through the chaining in the process and removed the override assignment options, there is no lane assignment and the expression rule returns just a single user.  Is there something I'm missing in the assignment process where it picks up previous assignees? Has anyone else had this issue?

 Discussion posts and replies are publicly visible