Your videos are being flagged for copyright issues
Recently Instagram has started removing videos from its API that contain copyrighted or potentially copyrighted material. This seems to include any songs or parts of movies that are longer than 1 minute in length (though it’s not clear exactly what will flag something to be removed).
You can try shortening the video or removing any background music to see if it will display in the feed.
You have IGTV posts in your feed
Instagram does not yet support IGTV posts in its API (which we use to create feeds in the plugin). IGTV posts are not displayed at all for this reason. If Instagram does support IGTV posts in its API the plugin will be updated to include these.