Users getting redirected to ADB2C Sign-in screen when doing change phone number or email with MFA exception

We are experiencing a strange issue with our application (all environments) where we are getting redirected to ADB2C sign-in (Custom policy with RestAPI provider and Identity API) screen intermittently when trying to change phone number or email. We have tried below so far but no luck - (checked from https://video2.skills-academy.com/en-us/answers/questions/69770/mfa-session-doesnt-work-in-azure-b2c-custom-policy?page=1&orderby=Helpful&comment=answer-70797#newest-answer-comment)

1. In none of our flows we have added prompt=login
2. We have tried adding <IncludeTechnicalProfile ReferenceId="SM-MFA" />
3. Validated OutputClaim and tried replacing the PartnerClaimType
4. We validated Risky users /conditional policies to check if its related to specific users or MFA

Additional information:

So far we have identified below two exceptions when it gets redirected to login screen.

• "A multi-factor poll request has resulted in an unknown poll response" - from browser network tab
• "Phone verification request is throttled" - from ADB2C user audit logs (we checked but could not locate any limits/restrictions which might be causing this)

Request you to share your inputs /suggestions on this which would be a great help.

Many Thanks.,

Anupam