I’m using WP 3.3.1 and WPEC 3.8.7.6.2 and everything works fine.
Please try disable other plugins – one of them might cause a conflict. I had a similar problem once with other plugin, it stopped working for no apparent reason and later it turned out that flip book plugin (which is using java to) was causing it and after disabling flip book all works great.
I’m using “Add TinyMCE to the Additional Description field” along with “TinyMCE Advanced”.
