I have updated basel theme withe the last version. Unfortunately the update of the version 4.12 to 5.0 of visualcomposer is not effective. I have checked the directory basel/inc/plugins/ and visualcomposer is not there.
We just checked our theme package on ThemeForest and it includes 5.0 Visual Composer version. Try to download it from your account on ThemeForest and reinstall Visual Composer with the one you will find in basel/inc/plugins folder.