To me its the same as any others we setup, there's nothing extra in the request url:
%globals_asset_contents_raw:xxxxxx%/s/search.html?collection=collection-name&profile=default&form=course-finder&%globalsserver_QUERY_STRING^replace:&collection=collection-name:%
maybe its the way the url is formed in the FTL, see below, tried stripping with replace but didn't work:
<#assign pageurl = QueryString?replace("collection=ulster-dev&profile=_default&form=course-finder&","")?replace("&userkeys=(?<=userkeys=).*?(?=&)","","ri")>