Thanks everyone for the help! I was able to fix as described in the post "https://www.mobileread.com/forums/showpost.php?p=3787648&postcount=409"
Basically there's an upcoming python hotfix / latest snapshot of python installation going to fix this issue. Until then wait or do it manually as the above thread suggest!
For now, all methods in librariansync works for me on PW3 and PW4. You people are awesome in helping each other
