Delegations seem to not work for actions that have user retrieved from form field

I have a participant group called Managers and an Active Directory group was created for the employees who belong to that participant group. The specific person to handle a request for the group is assigned by a form field and the action step setting “Retrieve Users From” has that form field selected. The Assignment Method is “Automatic To the person (one action assigned per user)”. This does work.

The problem I am encountering is when one user has delegated their work to another who is in the participant group. The “Delegatee” is not able to work on the action step. As far as I can tell the delegated person is in the participant group as well.

Thank you,