OutlookMobileCloudService - Add Account auto discovers stale / incorrect information, ignoring valid XML file

Question

Hi All,

• I have an IMAP and SMTP server of which their access details exists in an autodiscovery.xml.
• By using Outlook (2019's) "Test Email AutoConfigution" function, it resolves the correct information and all is OK.
• If I use the Mail 32-bit in Control Panel and Add the account, it is automatically detected.
• Outlook Connectivity Tester shows that the XML has been resolved / served / received all OK.
• Yet if I add via Outlook -> File -> Add account, it seems to use out of date information, and does not return the IMAP or SMTP details to the Outlook client. I can see the "OutlookMobileCloudService-Autodetect/1.0.0" service POSTing for those files all OK, but yet the detail is not returned to Outlook.

This can be simulated by using the following PowerShell command which does not return the XML and indeed shows stale information:

Invoke-WebRequest -Uri 'https://prod-autodetect.outlookmobile.com/detect?services=office365,outlook,google,icloud,yahoo&protocols=rest-cloud,rest-outlook,rest-office365,eas,imap,smtp' -Headers @{'x-email'="example@example.com"} | ConvertFrom-Json | fl

1. Why is OutlookMobileCloudService-Autodetect not returning IMAP, SMTP (or POP3) for that matter to Outlook, please?
2. How do I get stale / old information removed from OutlookMobileCloudService-Autodetect, please?