When a redirect happens and the URL contains a hash (#) everything after, and including, the hash is stripped from the URL
This is designed behavior and not a fault in the Episerver product, according to the RFC 3986 standard the hash symbol represents a URI fragment and this stripping is often done by the client browser and there is no work around for this.
RFC 3986 statement on fragments:
the fragment identifier is not used in the scheme-specific
processing of a URI; instead, the fragment identifier is separated
from the rest of the URI prior to a dereference, and thus the
identifying information within the fragment itself is dereferenced
solely by the user agent, regardless of the URI scheme. Although
this separate handling is often perceived to be a loss of
information, particularly for accurate redirection of references as
resources move over time, it also serves to prevent information
providers from denying reference authors the right to refer to
information within a resource selectively.