Ah,
Ok, did you know that Streamlit 0.84 has the release of the internally supported session state feature (no more SessionState.py required). I wonder if the presence of the old session state python file hack is causing a strange error?
Can you try using the new session_state feature in your code to see if that fixes it?
Check out our release notes: Version 0.84.0
also here is a link to the blog post on session_state: Store Information Across App Interactions | Session State
Happy Streamlit-ing!
Marisa