Ok, this is strange. I've been using this plugin for awhile now and it just started doing this. Only thing I did recently that may have affected things was restore my database to new version (updated the domain) but everything else is working exactly like it used to. This plugin is the only thing acting up.
What is happening is I click yes on "enable custom entry" and make a few other changes, but when I hit "save settings" the page simply reverts back to the default settings and "yes" changes back to "no" and no settings are saved. No matter what I choose, even if I only make one change, I cannot get this to accept any changes.
I also tried deactivating the plugin, deleting files, and re-uploading the latest version of the plugin downloaded from your site and it's still acting up.
What could be the issue here?