SSL Error when Initiating API

Hello I am getting the below SSL error when trying to initiate a call to API. I am on a professional plan and have the SSL check box selected in my app settings. Any help welcomed Please: Raw ERROR:

EPROTO 140635010840448:error:14094410:SSL routines:ssl3_read_bytes:sslv3 alert handshake failure:…/deps/openssl/openssl/ssl/record/rec_layer_s3.c:1544:SSL alert number 40

does the endpoint start with https:// ?

yes. the endpoint is