Line Manager delegating to an existing Line Manager

Summary:

We have a scenario where there are two line managers: Manager A is going on leave and as such, delegates their Line Manager role to Line Manager B (of course Line Manager B already has the Line Manager role).

The Line Manager role is custom and has a Person security profile based on Line Manager hierarchy with a Hierarchy Content of Both (see below).

When this role is delegated to another user (proxy) that does not already have the Line Manager role, it works perfectly and the proxy can see the delegator's direct report employees under My Team (the switcher appears on the top of the My Team -> My Team page with the assignment of the delegator, along with their own assignment).