Apple has made some recent changes to their operating system which causes problems with the 64 bit Mac AC3D 8.3.30.
If you upgrade your OS to the latest Mojave (10.14.6) and start AC3D 8.3.30 (64 bit) the Mac will crash out to the login screen.
For now, please use this Beta instead, and post any problems here:
www.inivis.com/external/ac3dmac8355.tgz