Fix eKYC 2FA Authentication

Our eKYC platform is live, but the two-factor authentication built into the public weblink is failing consistently. Users receive the OTP/SMS push, enter the code, and the process stalls with a generic “authentication error” before redirecting them back to the login page. Server logs show no obvious stack trace, so I need someone to dig in, reproduce the fault, and patch it without disrupting the rest of the flow.

What I know so far
• Front-end: React single-page component that posts to a Node/Express API
• Auth layer: JWT for the first factor, OTP via Twilio for the second
• Database: PostgreSQL 14
• Error appears only in production, not in our staging environment

Your job
1. Trace the call from the React form through the Express middleware to pinpoint why the OTP verification step breaks.
2. Repair or refactor the relevant code (JavaScript/TypeScript) so a valid OTP completes the login and issues the final JWT.
3. Suggest any security hardening or rate-limiting tweaks you notice while inside the code.
4. Provide a short summary of the fix and the files touched so my team can review and deploy.

You will receive Git access to a dedicated branch and, if needed, limited read-only production logs. I’m ready to test a working patch right away, so please indicate how soon you can start and roughly how long you expect the investigation to take.