Which PS Permission Groups Sync with Project Site Permission Groups - Getting different results

I have two issues I am looking for help with please

1. Which PS Permission Groups      sync with which Project Site Permission Groups
2. If I add a PS Permission      Group can I have this sync with a Project Site Permission Group

Background

I have 5 different PS2013 PWA systems and I get 5 different results when syncing permissions with the Project Sites. All 5 systems have both "Enable Project Web App Sync and Enable Project Site Sync" checked. 

Different results set examples

3 of 5 Portfolio Viewers sync with Project Managers (Project Web App Sync…)

1 of 5 Portfolio Viewers sync with Team Members (Project Web App Sync…)

1 of 5 Portfolio Viewers does not sync with any project site permissions

A non OOTB permission group (I added) sync with Team Members (Project Web App Sync…)

A non OOTB permission group sync with Visitors group

Individual users (member of one group only) sync with Project Managers (Project Web App Sync…), however other users in the same group do not

Working as expected…

If I add a resource to a project they appear in the correct permission group and the owner of the project also appears in the correct group

I have tested this with creating a new project each time. I have even tested it with the option in PWA Settings->Connected SharePoint Sites->Synchronize. 

Thanks

Andrew

Andrew Payze