Work item filtered from the plan

From the iteration plan view, I have created a new work item and immediately I see 'problem detected' message. This is becase the summary data for work item is blank. The issue is that though the draft work item is created it does not show up under the iteration plan.

When I try saving the plan an error message appears : This item cannot be opened and is currently filtered from the plan.

I have checked/searched for filters and could not find anything relevant.

Please advice.