When the OREDimmisemantor generates links to individual bitstreams it has a function to prepare the url for inclusion in the ORE document, escaping special characters suitable for a URL. That function escapes the forward slash character, which in the DSpace environment should not be replaced.
Here's an example of the problem:
The links generated in the example below escape forward slashes with "%2f", to produce a URL looking like:
but that url produces a file not found because Cocoon and the XMLUI can't handle the escaping of forward slashes. Instead this URL is resolvable: