What are the plugins you tried? I have a Moodle 2.3.2 and a 2.3.3 with no plugin issues? I don't recall any issues in 2.3.1 either. There is now the need to have the mod/plugin name:addinstance capability, however that has not prevented any of my plugins to work.
Also , are you running your Moodle on Linux? Could be permission issue.