It looks like you must have Curator or Manager privileges in order to batch edit the Project List, which is probably a bug because Admins are supposed to have all the privileges of Curator/Manager, plus more.
At any rate, the project Admin can’t easily get Curator/Manager status. Which means it takes two people to get to the batch edit screen. Person 1 creates the project and is the Admin, Person 2 joins the project, then is promoted to Curator or Manager by the Admin (Person 1). At that point, Person 2 can batch edit the Project List.
Alternatively, Person 1 can make Person 2 the Admin, and Person 2 can give Curator/Manager status to Person 1, then also give back Admin. Then Person 1 will be have both Admin and Curator privileges, including batch edit on the Project List.
Out of curiosity, is there a reason you’re using a Traditional Project over a Collection Project?