CommentStreams:0b9becf0fea528bfe97b13fe6bbca1b0
From The Lost Media Wiki
It's because it's IN STORAGE. Neither Jun nor IMAGICA have the rights to release the footage they own publicly due to some complicated copyright stuff. All we know is that the footage does actually exist.
btw, the copyright of the series will expire (depending on whether the series is treated as a cinematographic work) in 2023 (if it isn't) or 2043 (if it is)...