No. The Strike Industries Charging Handle Extended Latch is only compatible with the Strike Industries ARCH AR Charging Handle. The FX-9 uses a proprietary handle and will not work with AR15 pattern charging handles. Freedom Ordnance does make and enhanced charging handle for the FX-9, which can be found by using the link below:
https://freedomordnance.com/product/fx-9-enhanced-charging-handle/