This article only applies to App Layering 29.1 and before. In 19.2, the mechanism for getting the correct license changes to make it happen in the ELM, before the image boots. So you no longer need to worry about versioning your published image vDisk when Office is installed.
When you initially publish your vDisk into PVS, Windows and Office activation are successful. However, if you boot the vDisk in Private Mode or add a version to the vDisk in PVS, after you finish and assign the modified disk back to a Standard Mode target machine, Office activation is broken and Windows reports an invalid or missing product key. When you run Office programs, they will attempt to Repair themselves because their product licensing information has been lost.
After the edit, C:\Windows\Setup\Scripts\ActivateOffice_log.txt will show an error like this at the bottom:
Wed 02/06/2019-13:15:54.67- Detected VDI operation; forcing office activation
Wed 02/06/2019-13:15:54.73- Found File OfficeStd2016_KMS.txt - Activating OfficeStd2016_KMS
Microsoft (R) Windows Script Host Version 5.812
Copyright (C) Microsoft Corporation. All rights reserved.
---Processing--------------------------
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ERROR CODE: 0xC004E016
ERROR DESCRIPTION: The Software Licensing Service reported that the product key is invalid.
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---Exiting-----------------------------
ECHO is off.
Wed 02/06/2019-13:15:56.59- Activating Office using ospp.vbs
Microsoft (R) Windows Script Host Version 5.812
Copyright (C) Microsoft Corporation. All rights reserved.
---Processing--------------------------
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<No installed product keys detected>
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---Exiting-----------------------------