With the arrival of the new CoursePlus, faculty have more options when it comes to the administrative roles to which individuals are assigned in your course sites.
In the old CoursePlus, there were only two non-student roles: faculty and editors. In the new CoursePlus, there are many more roles: faculty, TA, site content editor, and guest faculty. The "Add TAs, Editors, Guest Faculty, and Guests" tool in your course site has the details about what each role can do, but there is one key change about the role of editors vs. the role of TAs in the new CoursePlus: editors don't have access to grading activities (including the Gradebook) in the new CoursePlus. The "site content editor" role in the new CoursePlus is really just that: a role for individuals like academic coordinators and administrative assistants to edit content in your site. It is not a role for people who need to enter grades in the Gradebook.
Your TAs should be put into the TA role in the new CoursePlus, not the editor role — unless you don't want your TAs doing any grade-related work.
When we were building the new CoursePlus, we realized that there was no way for us to know if an individual in the old CoursePlus was really a TA or what we now term a site content editor. We could not arbitrarily change everyone who was an editor in the new CoursePlus to be a TA in the new CoursePlus because that would mean giving a good number of people access to grades and grading activities who should not have that access.
For existing sites and sites you may create this upcoming academic year, you may need to go into the site and remove the editor role for someone who is a TA and give them the TA role instead.