sphinx-autodoc-typehints: Cannot resolve forward reference

Code:

if TYPE_CHECKING:
    from qc.model.user import User

...

    @property
    @abstractmethod
    def owner(self) -> "User":
        ...

Error with set_type_checking_flag = False:

WARNING: Cannot resolve forward reference in type annotations of "qc.db.Owned.owner": name 'User' is not defined                                                                                             

Exception occurred:
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/inspect.py", line 786, in findsource                                                                                                 
    raise OSError('could not get source code')
OSError: could not get source code

Error with set_type_checking_flag = True:

WARNING: autodoc: failed to import module 'app' from module 'qc'; the following exception was raised:
cannot import name 'User' from 'qc.model.user' (/Users/cyber/dev/jb/qc/qc-backend/qc/model/user.py)
WARNING: autodoc: failed to import module 'commands' from module 'qc'; the following exception was raised:
cannot import name 'TSTZ' from 'qc.db' (/Users/cyber/dev/jb/qc/qc-backend/qc/db/__init__.py)
... [many more]
cannot import name 'User' from 'qc.model.user' (/Users/cyber/dev/jb/qc/qc-backend/qc/model/user.py)
cannot import name 'User' from 'qc.model.user' (/Users/cyber/dev/jb/qc/qc-backend/qc/model/user.py)
cannot import name 'User' from 'qc.model.user' (/Users/cyber/dev/jb/qc/qc-backend/qc/model/user.py)
WARNING: autodoc: failed to import module 'test' from module 'qc'; the following exception was raised:
cannot import name 'User' from 'qc.model.user' (/Users/cyber/dev/jb/qc/qc-backend/qc/model/user.py)

Using sphinx-apidoc and python 3.7.