The issue is happening because not all your images and titles are the same size so it’s pushing some of them down. Try making sure that all titles are the same amount of lines and the images the same size before uploading them and they’ll display in blocks as they should.
I will however notify our developers of this and see if there is anything they can do to help this behavior.
Thank you Rebecca! Yes – all of the images have to be the same size and you have to have the same amount of text per portfolio item. If there is anything your developers could do about that, it would be most helpful!