I have found a further problem with the new 3.x.x plugin for me. With 2.0.4 no problems. All forced https pages looks normal.
If I do an upgrade to the newest version, I get a certificate error on one wordpress website. This page is forced by SSL and includes an iframe with a status update view (TeamSpeak Server) from an other php file. That php file is also opened through https. However IE and some other web browser shows after the upgrade to 3.0.3 an error message and no status update.
At the moment I changed back to 2.0.4, because there still other erros for me (for example missing RSS Feed...)
In this case I mean the following page: https://www.blackseals.net/teamspeak