Have someone seen unexpected error with AddBilingualReferenceFile method with Trados Studio 2019 SR2 -

FileBasedProject.AddBilingualReferenceFile Method (BilingualFileMapping) is causing the following error: 

Invoke Node System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
Inner Exception: Sdl.ProjectAutomation.Core.ProjectAutomationException: Bilingual reference file cannot be added
Inner Exception: System.UnauthorizedAccessException: Access to the path 'D:\perforce\Localization\Prj\Jp\SDLXLIFF\xxxx\SW\xxxxx\Resource.rc.sdlxliff' is denied. <append><b>System.UnauthorizedAccessException</b>

This SDLXLIFF file is on Perforce source code control, so unless we have it checked out, it is marked as Read-only.  When I made the file non-Read Only right before the method, the error did not occur.  Why is this method trying to modify reference file?

We have checked with Trados Studio 2019 SR1 -, and the error does not occur.

Any help is highly appreciated!

Rieko Matsunaga