Symptoms
AzureCSP APS. Option Use existing Microsoft account registered with us is not available (grayed) while customer does have active Office365 subscription and corresponding Office365/Tenant APS resource is consistent.
Cause
Office365/Tenant APS resource contains non-onmicrosoft.com subdomain in the initial_subdomain field. AzureCSP application does not support non-onmicrosoft.com subdomains currently.
Feature Request #PFR-1214: "Support of non-onmicrosoft.com domains" has been addressed to Odin Development team.
Resolution
Contact pta@odin.com or TAM to trace the status of the Feature Request.
Workaround: Use the Existing Microsoft Account Registered Elsewhere option on the subdomain form. The difference between these two options is - subdomain should be verified manually after this workaround is applied.