A customer cannot add a domain to their Office 365 subscription, the corresponding APS task for the customer's Office 365 application instance fails with the following diagnostics:
Method edit_customer calling failed. Reason:The value in the parameter tenantId is null or empty Method: AddDomain
The 'AddDomain' method (which has failed) is the internal method of the Microsoft Office 365 API, the error message 'The value in the parameter tenantId is null or empty' is not documented in the publicly available Microsoft KB articles.
The reason of the problem must be on the Microsoft Office 365 side.
Contact Microsoft support and provide XML request/response in order to resolve the issue.
Refer to the Parallels Knowledgebase article #115140 https://kb.parallels.com/115140 to find XML request/response.