The correct answer to this open question is the following.
The constitutional issues and/or questions unanswered in the U.S. Constitution as of 1860 tore the nation apart in 1861 were the following.
First of al, the issue of slavery in the Southern states of the country. Northerners supported abolitionism but the Souther states depended so much on slavery to grew crops in the large plantations of the South to export those crops. Other issues were the four-way election of 1860, the fugitive slave law and the feasibility of secession in legal ways from the Union. The United States lived in so much tension during those years and this represented the preamble of what would be the beginning of the American Civil War.