I have the Nestle-Aland Novum Testamentum Graece Editio XXVII, which I think is the SESB version. Anyway, it has apparatus in the text. When I click on those marks, instead of getting a pop-up, Power Lookup opens.
I have just checked and have exactly the same thing happening. Previously clicking the marks worked as expected.
I can reproduce this problem and have filed a bug report.