Why hasn't the UN been able to solve this long-standing conflict?

At a January 2018 meeting of the United Nations (UN) Security Council, Nickolay Mladenov, Special Coordinator for the Middle East Peace Process, said, “…all have fallen into a pattern of ‘managing, rather than resolving’ the Palestinian-Israeli conflicts.” He also said, “it was time to end this paralysis, show political leadership and push for policies on the ground that rebuild trust.”

However, the United States president, Donald Trump, has complicated the peace discussions at the UN and the structure of UN resolution voting makes it difficult to reach agreement. The UN situation is just as complicated and confusing as all the other issues related to the Palestinians and Israelis.