You should create a packet capture and enable logging on the proxy to see what is going on.
You have some options:* do not pass the traffic of the TV to the proxy (security risk because you will not see some traffic)* use a custom firmware on the TV which can set a certificate (risky to brick the device)* ask your TV vendor for a patch to fix the issue (takes time and may not be fixed)* don't use internet access on a TV...