[mbed-tls] Realization TLS 1.2. in libiec61850

Good afternoon, I'm trying to implement TLS 1.2. for MMS using the library libiec61850. When a connection is established, the interaction is interrupted at the stage "Client Key Exchange". Also, when monitoring the interaction through wireshark, I see that an error is displayed at the "Certificate Request" stage. I use default certificates, the project is built through CMake on Windows and TLS 1.1. works flawlessly. In the file tls_mbedtls.c I changed only the values of the minimum and maximum versions to TLS 1.2. Thank you in advance for your response.