Issue was resolved, I simply needed to start a conversation with some random person and Jaspar started speaking with me, and advanced the main story. Issue resolved in the meantime.

After being examined by Constantine I foolishly thought that I should be on my way and started to leave the sun temple, I remembered that I needed to speak with Jaspar so I could progress and reentered the sun temple. I was able to speak to him but I was stuck in the conversation dialogue and couldn...