I think it is the "Import job" object that users should have access to. It works on the PDMLink Excel Import. So I am guessing it is th same in Projectlink.
Write back if it works.
You got it. If the PM is also in the Guest role, for some reason the Guest role over-rides their PM access. Easiest way to fix this is to not use the Guest role for PM's and create a new role with similar limitations in Configure Actions for Roles. Check in with PTC Technical Support on this one. I believe CS171985 should address this.