FLstudio on macOS X and this functionality seems does not works here. It only works for native FLstudio plugins like 3x Osc, EQ etc. Do you have an idea how to set this things to work on the system ...
FLstudio, both don't work. However, both load the plugins fine from within the mixer effect rack.
I'm running FLStudio 20.5 [build 1142] (signature) on Windows 10 1607 14393.3115
For reference, the plugins in question can be found ...