I had problems with characters and the interactive renderer in one of my scenes. So I built a very small scene that can be quickly calculated with the interactive renderer.
As soon as I add a character to this scene, the IR renderer doesn't work anymore. It only switches between "parsing scene" and "preparing geometry".
Sorry that I still use the old release version, but I have to wait until the render farms have installed the latest version.
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Full-speed non-debug version
Build timestamp: Sep 5 2018 20:52:02
Version: B2 daily Sep 5 2018 (core 3 (DailyBuild Aug 17 2018))
Cinema version: CINEMA 4D Studio R20.028 S
Plugin status: initialized successfully

Logged
It's not the end of the world. But you can see it from here.
C4D R20 Studio on Win10, AMD 7950X, RTX4090
C4D R20 Studio on macOs 10.13.6 on iMac 27" i7 End 2015