SSH does not work with Duo Mobile two factor authentication.

When trying to use the ssh bundled with textastic I cannot authenticate to machines that require two factor authentication using Duo Mobile. Even though the push-authentication step succeeds from Duo, I always receive the error:

Failed to authenticate - methods: (keyboard-interactive,hostbased)

The Duo Mobile authentication works fine for other ssh clients on iPad, e.g. blink shell etc, so it must have something to do with the implementation on textastic.