Hello @Hamish Garvin,
Thank you for posting your query on Microsoft Q&A.
From your description, I understand you’re referring to Custom Controls (Preview) and are looking for information on when they will be available or supported for SSPR authentication methods during the verification process.
Currently, if you’ve configured a third-party MFA provider via Custom Controls (Preview) or External Authentication Methods (Preview), neither of these options meets the MFA requirements for SSPR. Unfortunately, we cannot provide a specific timeframe for when this feature will become available, as there is no set release date yet.
I would recommend requesting this on the Microsoft Feedback Portal. This is a great way to let them know how important this feature is for your organization. You can provide details about how custom control would benefit your use case and any other relevant information as Engineers constantly check there for features.
I hope this information is helpful. Please feel free to reach out if you have any further questions.
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Thanks,
Raja Pothuraju.