Broken 'lost your password' link

I am having trouble with the “Lost Your Password” link in a multisite installation but it is not the more typical “redirect to homepage” issue that other multisite users are having.

Clicking the “Lost Your Password” link goes to the following:
http://main.site.domain/sitename/wp-login.php?redirect_to=http%3A%2F%2Fmain.site.domain%2Fsitename%2Fwp-admin%2F&reauth=1

I can manually get a password reset by typing the direct URL:
main.site.domain/sitename/wp-login.php?action=lostpassword

What do I need to do in order to fix the link to go to ?action=lostpassword by default?