[Plugin: WordPress MU Domain Mapping] Plugins works, but settings page does not

I’m running 0.5.4.1 on WP 3.3 and it works perfectly, except that the settings panel doesn’t update when I click save. I’ve turned off w3total cache to check, and still the same issue… Anyone else experience this?

http://wordpress.org/extend/plugins/wordpress-mu-domain-mapping/