When I try to key in the information, I feel like it's not able to ready the Private key.  Not sure if anybody else had luck.

We are using Snowflake and use the private key and it works without issue. We have been using this setup for over 2 years. We saved the private key to a location that all Cognos servers could reach. This connection worked in both 11.1.7 and in 12.0.4.

Here is how we setup the connection string. 

Type: Snowflake

JDBC URL: jdbc:snowflake://companyspecific.snowflakecomputing.com/?private_key_file=//CognosServerName/FolderLocation/svc_sf_cognos-rsa_key.p8&useProxy=false&role=COGNOS_USER&warehouse=cognos_wh&client_metadata_request_use_connection_ctx=false&user=COGNOS_SERVICE_ACCOUNT

Connection properties: ibmcognos.subcode=SNOWFLAKE;

Driver class name: net.snowflake.client.jdbc.SnowflakeDriver

Connection string: ;LOCAL;JDBC;URL=jdbc:snowflake://companyspecific.snowflakecomputing.com/?private_key_file=//CognosServerName/FolderLocation/Security/svc_sf_cognos-rsa_key.p8&useProxy=false&role=COGNOS_USER_ROLE&warehouse=cognos_wh&client_metadata_request_use_connection_ctx=false&user=COGNOS_SERVICE_ACCOUNT;DRIVER_NAME=net.snowflake.client.jdbc.SnowflakeDriver;ibmcognos.subcode=SNOWFLAKE;