It is officially supported.

I have been running it under C3D 2021 pretty much since it was officially released by AutoDesk last year (and pre-release as part of AD's product testing group on test drawings). Have not had any significant issues. 

Seaweed,

We definitely support AutoCAD 2021 already, and have been supporting since mid May of 2020. Here is a link to the news article announcement where 2021 support is mentioned.

Monthly Newsletter May 2020

If you are not subscribed for our newsletters I would suggest doing so, so you are up to speed with the latest and greatest!

Thanks for your input Zman9119.

Thanks to you too Jake