@JustinB , It would be hard to state the reason without deeper investigation on this since most things are maintained by Backend in this Azure AD Domain Services, since its all a PaaS instance.
To troubleshoot this I would recommend you to get a support case created with us so that the engineer can take a look into your deployment and help you further.
Hope this helps.
Do let us know if this helps and if there are any more queries around this, please do let us know so that we can help you further. Also, please do not forget to accept the response as Answer; if the above response helped in answering your query.