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 ...
FL 20.1.2 and exporting in mp3 format is unable to render a simple automation consisting in diminishing the master volume et the end of a melody. The same thing occurred with the previous version but it has already worked with ...
FLStudio installation folder. e.g. CD C:\Program Files (x86)\Image-Line\FLStudio 21. Then enter: All projects in a folder (including sub-folders) using a complete path - FL.exe /R /Emp3 /F"c:\src\", where c: is the target ...