"The specified path is invalid" error in "Backup Translation Memory" in Fragment Alignment Support, on Mac OSX.

Any help much appreciated.

Mac OSX 10.13 running Parallels Desktop running SDL Trados Studio 2019. 

Fragment Matches delivers no results.

Attempted fix: Project Settings->Translation Memory->Fragment Alignment->Fragment Alignment Status->toggle from ON to OFF then back ON->pop-up Fragment Alignment Support "Do you want to proceed?"->Yes->pop-up Fragment Alignment Support: first step, "Backup Translation Memory", fails, with message "The specified path is invalid"->View Log File:

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Backup Translation Memory (22/5/19 12:33:40 am)

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Backup location: \\Mac\Home\Documents\Studio 2019\Translation Memories\MSS_March19.sdltm.000.bak

Process failed (22/5/19 12:33:41 am)

System.IO.IOException: The specified path is invalid.

   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)

   at System.IO.File.InternalCopy(String sourceFileName, String destFileName, Boolean overwrite, Boolean checkHost)

   at System.IO.FileInfo.CopyTo(String destFileName, Boolean overwrite)

   at Sdl.TranslationStudio.Common.Helpers.FileService.CopyTo(String existingFilePath, String newFilePath, Boolean overwrite)

   at Sdl.TranslationStudio.Common.TranslationMemory.TranslationMemoryAutomation.Jobs.BackupTranslationMemoryJobRequest.Execute(IJobExecutionContext context)

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Update translation memories finished. (22/5/19 12:33:41 am)

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