@colin-wright This is very likely a problem with VST3 integration. I would suggest you use VST2 instead because you said it is working fine. This problem will likely not go away without an update to the VST3 integration in ACID. But there was a very long time no new version or upgrade to this software. As an alternative you could use a plugin that can host other plugins, for example Plogue Bidule, which I can fully recommend.