Subgroup administrator not able to invite new members

I have a subgroup and made one of my members an administrator. However, despite me ticking the box that says administrators can invite new members he doesnt get the option to invite members himself.

I tried removing his permissions and then reapplying them - made no difference.

What needs to happen to allow him to invite members?

Also, just fyi, this isnt my normal account in the Champions group, I had to create an entirely new one in order to get in and report this error (as for whatever reason the group isnt recognizing my account or my email address etc)

Pete