This is a common mistake. You're running searches like
when you should be running
stats count by foo
instead. The former will return just one row, with "values(foo)" as a multivalue field. However it is designed for situations when there are only a few values, so it truncates at 50. The latter on the other hand will display any number of rows - hundreds, thousands, millions, and never truncate.
Similarly, if you find yourself doing stats values(foo) by bar, intending to get unique combinations of foo with bar, just do stats count by foo bar.