First, Proxy recording does not support multi protocol.
A possible reason of the failure is the app uses very strict security policy and denied the fabricated certificate from LoadRunner, or uses some client side certificate. That's not easy to solve. The testing engineer need to obtain the corresponding certificate.
I tried the APP and only student of the university can login to it. Are you from the DEV team of the APP? Or can you get the security policy information fromt he DEV of the app?