We're doing things backwards, we have an established o365 domain, with 400+ users, and are just now deploying local AD, and ADFS for SSO.
Last night, after configuring my servers, I ran the powershell command convert-MSOLdomaintofederated to convert the xxx.com vanity domain to federated, it errored out with an unspecified error(Microsoft ADFS support said the error has to do with the default password settings being changed.) And when I run convert-MSOLdomaintostandard, it comes back with the domain is already standard. Also in the o365 portal it shows the domain as standard, however it is trying to process login attempts as if it were a federated domain.
I've spent 5 hours total on the phone with Microsoft, and it has been escalated to their engineering department for resolution, sometime within the next few days... I need it yesterday.
From what we can gather, the conversion process started, error out, changed some of the internal configurations to federated, but left the description as standard.(if that makes since). So its in a weird limbo, where its in both modes but neither at the same time.
Currently, the only way to fix it is to remove the vanity domain, and re-add it.
I need a way to dissociate the user accounts from xxx.com domain to allow its removal. Removal of all the users themselves is not an option.