The most challenging and important problems to solve in an engineering organisation are rarely technical in nature.
The interesting question is what sort of jobs contain a lot of challenges that are technical in nature.
At one of the places I worked, I got to implement a request batching algorithm using dynamic programming, at another place I got to implement a nurse rostering algorithm (this is not as easy as it sounds, and is an active research area), and at a third place I implemented the recursive tree algorithm that keeps a lookup table of user permissions up-to-date in a situation where roles inherit permissions from other roles.