Add Assignee Below Participant (which is custom role) not working after 23D

Summary:

Our process for some Request New Position approvals is to Add Assignee Below Participant. Since 23D this is not working.

Content (please ensure you mask any confidential information):

When we Add Assignee Above Participant it works, but Below it doesn't - this has only been the case since 23D and only relates where the Participant is an Application Role.

See screenshot below a number needs to be allocated to the Section between 1.5 and 1.6 when we select Apply the Participant where no number is allocated against the Section disappears.

I have checked the Approval Rule, Deleted the Original and Recreated but no change.