App rejected due to IPv6 error when selecting the menu in the upper right corner

This is the first time my Ionic app has been rejected based on this problem.

Your app crashes on an iPad and iPhone running iOS 9.3.5 connected to an IPv6 network when we select the menu icon in the upper right corner.

This occurred when your app was used:
- Offline
- On Wi-Fi

We have attached detailed crash logs to help troubleshoot this issue.

I have looked through the forums and most of the IPv6 questions are related to the network issues i.e. connectivity, but in my case this reads like a purely UI thing. Any help?

fyi, my app uses an older version of Ionic i.e. Ionic, v1.0.0-beta.13