short code to show invite form does not work?

hi,

first of all, amazing plugin, thank you!!

here is one issue, though: i created a page “invite a friend”, and used shortcode [inviteform]. When I am logged in as admin, it works fine. However, whenever i log in as a user, invitation form disappears. Please help! Thank you!

And yes, the user was invited.

https://ww.wp.xz.cn/plugins/wordpress-mu-secure-invites/