Was this a 32 bit VST-2 plug-in? That particular behavior appears to be the same issue with Sound Forge 16 and 17 (pro and AS), and in Vegas versions from the same time period. I was forced to use earlier versions to use my 'go to' VST-2 plug-ins to get a desired sound. It seems to have been resolved with Sound Forge Pro 18 and Vegas 22.
FWIW, there is no Sound Forge Audio Studio-18.. only SF-18 Pro so SF 16+17, which are unusable if you need to tweak a 32 bit VST-2 plug-in preset.