Update Jira to 7.12.0
It shows in Applications menu that new version is available. I wasn't able to update a few plugins showing there is a new version for them. Maybe because of new version of server available. Or maybe because of bug which maybe is fixed in 7.12.0. Also log analyzer shows a bunch of errors (one has 7000+ occurances). Hopefully update will fix some of them.
upgraded. Indeed, the filled disk was causing troubles.
Maybe something else is wrong. When i have posted this and is wasn't actually appearing in the system for a while (not in activity, nor in the list). I have tried to re-run indexing and it failed. But then two new tickets appeared in activity.