Seamless migration - First time login is failing with Application identifier error

[AbdulMohammedB2C]

I am facing issues with B2C seamless migration process.

The first time a user logs in, they are successfully validated against the legacy IdP via a web service, their 'requires migration' flag is successfully flipped to 'false', and their password is successfully written to B2C. However, when they hit the step 'login-NonInteractive', it is not authenticating them correctly and shows the error message "The application with identifier {proxy identity framework application client id} was not found."

But when I click the Sign in button again it gets logged in properly,

Appreciate if anyone can help here.