Hey there @shehan.f, I apologize for the delay in responding so late.
If this particular user is still battling MFA issues I would be happy to assist. If you could please direct message me the user’s username/email paired with the tenant name we can take a look at what is different about that particular user to begin with. I also have included for reference our MFA Reset Request FAQ topic.
I understand that this topic was generated quite some time ago so I will keep this topic open for 10 days just in case this is a hurdle you are still facing. Thank you.