Problem creating custom roles for a project

I have a problem setting up basic role management. I am trying to create a custom role 'ContentAuthor', but I cannot seem to properly configure the system to let users access modules in the backend, and I cannot quite see what I am missing. Here's what I did:

• I created an MVC site 'Site1'
• I created a role 'ContentAuthor' for Site1
• I gave ContentAuthor permission to Read and Manage 'A/B testing'
• I personalized ContentAuthor via UI personalisation by choosing "select all" under the CMS node.
• I added A/B testing to the default Dashboard for the ContentAuthor role
• I created a user "Writer" and who is available for Site1 and has role ContentAuthor, who is enabled and has privilege level 'editor'
• I checked in Modules -> A/B testing -> User Interface for Site1 that the checkmark is set, and I checked this for all of its parents
• I checked in the permissions module that, indeed, ContentAuthor is permitted to read and manage A/B testing for Site1

Now, when I go to the Dashboard while Site1 is the site I am currently editing - displayed next to the Home button - and start to impersonate Writer, I cannot access 'A/B Testing' module. 'A/B testing' is not displayed on the dashboard (only the welcome tile is shown) and the module menu only shows 6 modules that seem unrelated to what I did (Checked-out items, My Blogs, Recycle bin, Friends, Messages, My Profile).

I have tried out variations of the actions above, including creating a global role and user, trying other applications, disabling UI personalization and assigning the role to a membership, but could not make any headway. Where do I go wrong?