All projects have problems. Inexperienced project managers believe that sufficient time exists to solve these problems only to discover that the costs of correcting these problems later on in the project life cycle was significantly more expensive than making the repairs in the earlier stages of the project. Remember the 1-10-100 rule. What costs $1.00 to fix in requirements costs $10.00 to fix in planning and $100.00 to fix after the project is delivered.
Project managers cannot be selective in which problems to solve. All project problems must be addressed, and the sooner the better. While it is true that project managers may not be able to solve the problems themselves, they should at least know what subject matter experts they need to address the issues.