Side chain missing?

I saw lots of publicity for improved side chain functions in C10. I’m a user since 8.5 on Windows 10 and can never get the side chain button to appear at the top of the plugin. Fabfilter Pro Q2 is a fav plugin of mine and is love to use its side chain functions- but even now in Cubase 10 I can’t get the button to appear. Is there a setting I’m missing, or are 3rd party plugins not supported? … on Steinberg own plugins I can get the side chain button to appear. Any suggestions?

Thanks
John

Use the VST 3 version of FabFilter. The VST2 version does not have this feature.