On my end it works on any given page, home, subpages, regardless of the URL. I tried to trigger the error but no luck unfortunately.
If you want, you can add temporary FTP and back-end access, I can take a look.
Before that I would start by removing any custom code you may have, disabling all plugins temporarily, reverting the .htaccess file to default to see if anything changes. If it works then, then there is a conflict somewhere. If not, then it is still possible that the borwser just does not trigger a location change only based on the hashtag without query arguments.