Issue with uploading identity certificate for two-way SSL

Summary:

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My organization is trying to set up two-way SSL for communicating with our middleware service. We have shared our certificates for OIC with them and they have provided us with a .jks file.

The .jks file contains two public key certifications and when I try to upload the .jks file to OIC I am encountering an error (depicted in screenshot).. the two certificates are public and are not password protected, but I am still getting this error. We were able to upload one identity store with an additional leaf certificate, but even still the leaf certificate is public and not password protected.