"Root issues" refers to the fundamental or underlying problems that cause a situation or issue to exist. It points to the core causes that need to be addressed in order to effectively solve or improve the situation. Full definition
A consistent, intensive experience enables clients to resolve root issues and achieve treatment goals. (safeharbor1.com)
For instance, if overwhelming feelings arise because you become very worried, address that root issue rather than not taking a risk. (entrepreneur.com)
That's the real root issue — not the porn alone. (mindbodygreen.com)