I’m running the latest 2.6.0b1, and when I click Resend All Invites (I have 619 pending), Discourse says that all invites have been resent, but nothing happens at all. The Last Sent date does not update, and no email goes out (I’ve checked in Admin > Emails > Sent). The problem existed in the previous version too, since I updated to verify that it hadn’t been fixed.
Sending of an individual invite does work—I tested that with the first one in the screenshots below. The date updates and I saw outgoing email in the Sent log.
Clicking Resend All Invites
Showing All Invites Resent (except not really)
I’ve increased the number of days of invite expiry from 30 to 60 so I hope these invites don’t all disappear on me tomorrow. 
I see what might be another instance of this bug at Resend 1.5k invites does not work
