At Admin advanced search, if it the search include a ccode filter (limit), if opens a record, and try to go back to results... you will get always 0 results. koha forgets the ccode limit , the url is like /cgi-bin/koha/catalogue/search.pl?idx=kw&q=a*&limit=&limit=mc-ccode: no ccode and it always gives 'No results found No results match your search for 'kw,wrdl: a*' with limit(s): 'mc-ccode:""' in ByWater Library System Catalog. '
This should be fixed by bug 20529. *** This bug has been marked as a duplicate of bug 20529 ***