Logout on blog preview 1.7.4

Hi all!

I'm running Elgg 1.7.4 and every time I preview a blog post, it logs me out and tell me that I need to be logged in to view the page. (it's also documented here).

Here's a run down of what happens:

Steps to reproduce:

-Loggin as admin

-Create a blog post

-Edit post and save. Editing is ok.

-Edit post and click preview -> loggout


-Edit post (no modification) and click save.

-Edit post -> blank fields title and content...

Then, if I create a new blog post I now can edit the last, that was blank before.

Does anyone have this problem?
The error does not happen when I am running it on my local setup, only on my live site.

Any help would be greatly appreciated!