The Ohio Secretary of State’s web page has this link to preliminary, unofficial primary election returns. Ohio held primaries for the Constitution, Green, Libertarian and Socialist Parties, as well as the Democratic and Republican Parties, on May 4.
The Secretary of State’s election returns do not say how many voters chose the primary ballot of any particular party. But from the returns for the statewide candidates, one can know that at least this number of voters chose a minor party ballot: Libertarian 4,255; Constitution 1,737; Green 882; Socialist 369. It is true that the Libertarian Party candidate for Attorney General is listed as having received 6,146 votes, but this is almost certainly a mistake in the preliminary returns, because all the other statewide Libertarians received between 4,120 and 4,255 votes (each was unopposed), and it is wildly unlikely that approximately 2,000 voters would have chosen a Libertarian Party primary ballot and then left all the statewide offices blank except for Attorney General.