I noticed that there's been a similar issue with the version 1.7 here.
However, I'm using the latest version 2.0.2 and the plugin just stopped working for me.
When I just downloaded it, the plugin was working and when you went to the "Ask a question" form, there were two categories in the dropdown (Unsorted and My Own Category Name). The whole journey from asking to answering a question worked fine.
Then I deleted My Own Category and created 15 new categories. After that the "Ask a question" form stopped working. The category drop-down list is very very narrow (just a few pixels) and you cannot actually select any categories. It just pops out with a long list of empty spaces. Obviously, without selecting a category, it's not possible to add a question.
I did what you suggested in the aforementioned 1.7. version solution but it didn't help. I also deactivated and deleted the plugin, then reinstalled but it has kept the settings. Do I have to dump the whole installation, clear the database and start again?