K2 comments not working when logged in

I wanted that only my registered users should be able to comment on my articles, but when doing this change there's no longer any chance to write comments to my K2 articles.

If logged out it says "Please log in to comment", but when logging in it's blank. Zip, zero, nada

Hotstart, only extension installed afterwards; Kunena.

Not edited any files after installation.

On this k2 forum they say in that case you need to change your login is set. Users need to login throe k2 login module of k2 users page. So you remove default joomla login menu item and replace it with k2's:

getk2.org/community/New-to-K2-Ask-here-f...tonly-for-registered

Well, turned out it was as simple as me being the Super User only and not in the Registered group..

meh.. ah, well, somebody else might run into the same issue so just make sure your super user also is in the Registered group in K2 and you're all good to go.