Found the solution this evening, it is a nginx issue:
For those using nginx, try to find those lines using wp-admin in nginx.conf, with a focus on any line forcing wp-admin using SSL – it just creates a conflict with admin-ajax.php
– yes, it’s not enough disabling SSL in wp-config.php
Of course remember to reload nginx after the updates.
I’m also using the Buddypress theme (to test) and having the same issue with the post update button (never stops looping and no update is made). I disabled FORCE_SSL_ADMIN after you mentioned that, but I’m still having the same issue.
Sounds a server configuration that it’s wrong (as I’m using a new wordpress installation a NO plugins are active at all)
Wondering if you manage to get the source of the issue and help me, or you are stuck yet with it.
