If its my turn to ask a question, and the other actively chooses to not answer that question, have had plenty of time and opportunity to do so, and they don't articulate why they are unable to answer, I respectfully decline to continue engaging on the topic and with that person. There's either something intentional or unintentional happening, both of which indicates its not safe.

If they have a good-faith concern relevant to the matter and they put it at the end (after they have answered that which was solicited) I am often more than happy and open to engage and continue in that vein of discussion