FLStudio's plugin manager is not up to date with the latest versions of the SDK.
This was taken from the page "VST 3 Locations / Format" in the SDK documentation:
[quote]
On the Windows platform a VST 3 Plug ...
Hi everyone,
Please does anyone know why some of my vst's wont be found on my FL-12, but if i switch back to my FL 11 everything works well.
Please any ideas?
Thanks.
Ziwo ...