Other problems with networkwide search: 1. It only displays 15 result per site, although (by default) it says 30. 2. If you try a search which has about 30 results, you do not have access to the next page of results (unless you manually modify the URL). 3. Basically in any search, if you go to the last page, you see only 15n (rather than 30n) results - you can see additional result by changing page=n part of the URL. — Martin Apr 22 at 5:32

4. If you switch to 50 results per page, this setting is forgotten when you go to the next page of results. A similar thing was observed here: Does network-wide search for tags work only with is:q? I was considering posting a bug report about this (mainly about the problems described in the previous comment). But all things described there are probably caused by the same problem as the ones described in your question. — Martin Apr 22 at 5:35