cannot find reference 'xxx' in '__init__.py'

[julingers]

I installed nvidia-tensorflow successfully based on RTX3060, ubuntu22.04LTS. I checked that GPU is available and my code can run normally. But there is onething I cann't explain it. Some tf functions in Pycharm IDE usually show 'cannot find reference 'xxx' in '__
init__.py', like tf.train, tf.summary, tf.nn and so on. I can't get inside the function although the code can run normally. Why is it? Can anyone help me?