I had the same problem and I solved it by using an absolute import instead of a relative one.
for example in your case, you will write something like this:
from app.mymodule import myclass
You can see in the documentation.
Note that relative imports are based on the name of the current module. Since the name of the main module is always "
__main__
", modules intended for use as the main module of a Python application must always use absolute imports.