It is possible that your computer is below minimum specifications and that is why the Rebuttal Showdown is not working. On the official Discord server there is a LowSpec build that should fix or at the very least attenuate this issue.
In the pinned post of the #public-testing channel there is a link to a post titled "Low Spec Version Chapter 1 Testing Thread (CHECK PINNED MESSAGES)". There, you can find a link to download the latest LowSpec build.
