So my client managed to find some (bug?), when custom post is published and he previews post all information what is posted with custom meta boxes is inaccessible. When I started debugging I found that in this case get post meta returns empty. Someone know why system acts this way.
And yes, when i look at post not prview all information shows fine. And before posting get_post_meta() works okay. Only in this case where post is pubished and preview is clicked.