Yes, I found that with the new version of wordpress and your plug-in, that in order for the drop down to work properly on the registration form, I needed to do make sure I completed all areas at one time, or certain things would just 'not work'. (In other words, the first time I installed the plug in with the latest version, I filled in the company information section, categories and events, but not the payment; as I had to go take care of something else. When I came back to finish filling it in, for some reason the drop down box on the registration form wouldn't work. So I uninstalled everything, filled it all in from scratch and the drop down worked.)
Everything works great except for the authorize net pay now button. If I use paypal instead of authorize net, then the pay now button will be show up.