Dynamic Form Rules with Related User

End goal is I need to pull over a phone number for a user. So currently I have this setup:
Two tables: Employees, Pay App. Parent table is employees, child is Pay App.

Employee Table includes Fields: User, Phone Number.
Pay App Table include Field: Related Employee, Employee Phone Number (this is just a lookup field), Project Manager (this is a user field, and is a lookup field from a third table).

I want to be able to set the related employee to the project manager. I was attempting to do this with a dynamic rule. So I tried as my action 'change' 'related employee' to the value in the field 'Project Manager'. This doesn't work because it is looking not at the user names, but the Record ID's..

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Mike Tamoush
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