There are two possibilities: Either the item(s) are marked as Admin or there is a Rule that is hiding it.
First, edit your form and locate the first unseen item, then edit the item to see if its Admin Item setting is turned on. Admin items are not shown on the form and only appear in the results table, so if you want the item to appear on your form then de-select this setting.
If that is not the issue, edit the item and click the Rules tab in the settings window. There you can see the Rule that is hiding the item and the condition necessary for it to show.