A page name is subject to a few rules because it passes through our servers via the HTTP protocol. If you do not follow our recommendations, it is highly possible that the "page" parameter will never be collected and moreover, it will block the rest of the hit.
If you want to use the "#" character in a page name you will need to encode it in UTF-8 format, otherwise, it will erase everything after this character. So to use a "#" you just need to replace it with "%23".
You will find the general rules on accepted syntax by clicking on this link.