Strange problem with image attachments.

[HendriXXX]

Hi!

I have strange problem with image attachments. Seems like I cannot find the reason.
Smf version is 2.1 latest "commit fa03a55". No mods installed.

For some reason I cannot preview image attachments as regular member. It uploads image fine, it get posted fine, but when trying to preview message with image "attach" code it says "You cannot see attachments on this board.".

This also happens when trying to modify userss own message and try to preview it. However it looks a bit different. I doesn't show little thumbnail at all and it shows that little broken image icon. When I try to open image to new tab, it says 404 or something.  See attachment..

Regular member group has attachment rights. See attachment.

I can preview attachments in posts as Admin, so that makes me wondering what right I am missing..
Probably it is some simple thing what I just can't spot from settings.. 

Any ideas? Thanks!