Non-authoritative answer:
mail exchanger = ms55938458.msv1.inalid.outlook.com
Missing the "V" in invalid the MX record and the TXT record both are using the same "MS" number.
Delete all DNS verification records and only use the TXT record. When you delete the record a NEW "MS" number will be generated.
Remove old account as described in my last post.
Add the domain again and wait 1 hour
Go to portal.microsoftonline.com and click verify now.