Nevermind. It appears users can only claim (take ownership) of a ticket when a department is chosen and the field to assign the ticket to a specific user or team is left blank.
If a Department and Team are chosen, then the ability to take ownership of that ticket when emailed to everyone on that team or department is lost.
So, if you want your users to have the ability to claim or take ownership of a ticket, only select the department the ticket is for. Though it would be nice to be able to take ownership of a ticket when assigned to a team as well. I have just stopped using Teams...