Can't click on link in web database

There's a web database at my school in which we need to enter feedback for students. There's a blue underlined hyperlink one should click on, but with my recent Xubuntu AND Lubuntu installations, trying every browser available in the repos, clicking on the link gets no reaction (there should be a popup window where you enter the info -- i've tried enabling all popups and allowing the schools website all permissions.... no joy).

Inspecting the element in firefox gives the following:

<a id="GridView1_mod_0" onclick="window.showModalDialog('TeacherAttendClassDetail.aspx?studentId=100134&amp;schoolRegionId=8&amp;timeSegmentId=10&amp;classroomId=6&amp;date=2018/12/16 0:00:00&amp;classTypeId=1432&amp;classGradeId=1664&amp;classSerial=6','12','dialogWidth:430px;DialogHeight=285px;status:yes;resizable:1;center:no;scroll:no') ; window.location='TeacherOrderClassDetail.aspx?schoolRegionId=8&amp;timeSegmentId=10&amp;classroomId=6&amp;date=2018/12/16 0:00:00&amp;classTypeId=1432&amp;classGradeId=1664&amp;classSerial=6';" style="cursor: pointer; color: Blue;">Modify</a>

No idea what to do with that. Never had this problem with my previous linux distro-hopping. Any help appreciated.