The biggest issue with math is that some students are simply better with languages. However, they are not capable of understanding math 100% and impressing their professors. It is almost impossible that a person can be a genius in math and languages simultaneously.
The second issue is that some students have poor basic math skills. This can occur due to so many reasons. In that case scenario, a student is unable to master more complex problem-solving processes. Ideally, you will go back and master basic skills and then move to more complex ones.