This is a brilliant Irish Times Article from Northern Ireland Newsletter journalist Sam McBride - someone who knows the N.I Executive and its workings very well.
It explains the deep issues with the NI Executive and how the differences and the system itself has led to years of problems which don't look to be sorted any time soon
https://www.irishtimes.com/news/ireland/irish-news/silos-secrecy-and-quiet-deals-how-dysfunction-became-stormont-s-norm-1.3756468?mode=amp