It's possible, certainly. There may not be anything in the code that the reverse-engineering process recognizes as a UML relationship. Precisely what that would be depends on the language and tool, since there are no standardized UML profiles for any implementation languages.
UML is fundamentally object-oriented, but in Python, object-orientation is optional. If the code doesn't use classes, there isn't much for UML to work with. Python's dynamic typing also makes it tricky to deduce the types of variables from the source code, which means it's hard for the UML tool to identify associations.
In EA, there are some options you can play with under Tools -- Options -- Source Code Engineering. On that page there's "Create dependencies for operation returns and parameter types," which I believe is off by default. But since EA treats all Python types as var
I don't think this would have much of an effect.
There are further options per language, but I don't think there's anything in the Python section that affects relationships.