Reference: https://www.mediawiki.org/wiki/Extension:VisualEditor#Changing_active_namespaces
Per https://en.wikiversity.org/w/index.php?title=Wikiversity:Colloquium&oldid=1997427#VisualEditor_Active_Namespaces , please set $wgVisualEditorAvailableNamespaces to true for the following nine namespaces:
Default:
main
Category
File
User
Custom:
Draft
Help
Portal
School
Wikiversity
Thanks!