I developed a few programs that runs well on Python 3.5.4, but because of some errors about win32 made me go to Python 3.6.4, but when I build my project with pyinstaller, I get
I had the same issue which is apparently a known bug due to sip now being installed separately.
sip
https://github.com/pyinstaller/pyinstaller/issues/3630
Upon creating the installer I added the line:
--hidden-import PyQt5.sip
This worked no problem.