We have upgraded from 1.9 to 2.4 over the summer and have been tweaking things to get them working properly. One issue that I can't seem to locate/resolve is importing quizzes into any of the upgraded courses (1,500+) does not work for the teacher role. Site admins can import just fine, but teachers do not have the rights.
We had an issue just like this with new activity and resource types not being available in the drop down menus or Activity Chooser. Permissions were set to -1 for the teacher role on Adding those in the database so changing them to 1 did the trick.
I am thinking it might be similar because teachers can import into Newly created courses. Any help is always appreciated!