When clicking "Load repositories" after filling in my username 'stain' when creating a new Plan, only the first 30 or so repositories are listed in the dropdown box.

This is likely due to Github APIs pagination - see https://developer.github.com/v3/#pagination

e.g.

bash-4.1$ curl -s https://api.github.com/users/stain/repos | grep \"name\" | wc -l
30