Hi @john_barr, I cannot duplicate the behavior you are experiencing with (VST-2 (x64) and VST-3 (x64) LoudMax. v1.42 functions normally as a single plug-in and in a Fx chain. I tested with SF Pro-15 and 16.1 (current builds) on a Win 10 PC with the latest update.
It's unfortunate to see software that has been around for a long time getting worse. Other DAWs (Audition, Reaper) don't have the problems that Sound Forge does. Some people don't like the complaints I make. I would like to see Sound Forge running smoothly. But that seems impossible.