This paper captured what I encountered as a TA in the 90's: students could solve the integral forms, but had trouble with the differential due to fields. I think this is because some students have a very difficult time going from the mental image of fields as 2D arrows, to div, curl and grad in practice. There's a big step function there in manipulating the equations. I wasn't a very good TA because I didn't have much luck explaining to the struggling students (still feel bad about that, sorry folks, I was getting my master's degree and had no choice to be a TA). And students who didn't understand this in second-year physics had even more trouble when their EE classes went into field and waves classes (conductors, antennae, etc.).

TL; DR: I think this is more a problem with teaching advanced differential calculus concepts than Maxwell.