New issue with button sets and pick-many questions

Our team designs KC questions as 'pick many' and then assigns the responses to button sets to make them behave as 'pick one'. This allows us to design one question and then adapt it to single selection or select multiple. The new issue revolves around the button set. Using the default button set 'Button Set 1' will break the question. When you submit, it thinks no selection has been made. I have created a new button set and the question works as expected. While this work-around is good going forward, we will need to make modifications to legacy courses that use the default button set I'm assuming.