I have been noticing this issue since I started using it on Multitsite, whenever I try to edit user capability from wordpress multisite network dashboard by following
User Role Editor
Other Roles >> Edit (by clicking this)
brings me to this page
and says "You do not have sufficient permissions to access this page."
I am "Super Admin" means there is no access issue.
I have tested it on several multisite installations, specially on my localserver but no luck :(
I even dig into code and was unable to trace the code so I could let you know the culprit :(.
Note: I can easily edit user capability on specific subsite dashboard or on mainsite but I cannot go and change user on all subsites (imagine having dozen of subsites :()
Please have a look and suggest a fix????