How to apply person security in BPM Vacation Rule

Good Morning,

We ask our Line Mangers to set a BPM Vacation Rule when they are absent to reassign any items for approval to another manager. Items for approval include (but not limited to) Absence requested, Expense approval, ICPs etc.

It seems the "Identity Browser", used to search for a person in BPM, does not respect the Public Person Data Security, and displays the names of ALL users in the system.

We run many external payrolls, and do not want our Line Mangers to see outside of their own Business Unit. A Public Person Data Security profile is attached to the Role these user have, which works on the main Fusion screens, but not BPM.