Hey @DannyT, thanks for your patience! Looks like Jay has been responding to you in email. 
This looks like a one-off issue specific to your form rather than a platform-wide bug. Your data is all still safe in RetoolDB! In the meantime, you could use Retool Assist to build a custom view of your form responses, it's pretty easy to set up and will give you more flexibility than the built-in response summary. Let us know if this workaround works well for you! Thanks! 