I ran into the same issue when installing the Trakt add-on.It turned out that Trakt didn't install because installing script.module.dateutil failed; and installing script.module.dateutil failed because installing script.module.six failed.
I managed to install Trakt by first downloading the zips of both script.module.six and script.module.dateutil from Files..., and installing them manually in Kodi. Then I could install Trakt without issues.
Thanks a million for this! I did a clean install of v7.90.006 recently and was also struggling with trakt.
