[Solved] Why does the ProtectedFromAccidentalDeletion property on the Get-ADGroup command in the PS AD module return a NullReferenceException on one machine?

This is a bug in PowerShell 6. The resolution is to upgrade to PowerShell 7, where it was fixed.

Reference GitHub issue where the issue was first reported & marked fixed:

SteveL-MSFT commented on Aug 23, 2019:

This is fixed in PS7 Preview3

_{(See also https://github.com/PowerShell/PowerShellModuleCoverage/issues/8)}