I am having a issue. The datasource editing seems to disabled for a particular role "Regional Content Author" but is enabled for another in sitecore content & experience editor.
I have analyzed that both the roles have read & write ability for the items (for which we want the datasource to be edited) in the Access Viewer.
Can someone suggest what may the issue?

Edit datasourceicon missing? Field disabled? Some other issue? Have you checked "Write" access rights for theDatasourcefield? - Marek Musielak