I have 2 custom guns in my map. I got the 400 fx error and I downloaded the fx fix and whenever I delete some fx in my zone_source/english/assetlist/my_ignore.csv and when I build the mod and compile the map and start it, it still says I reached the 400 fx... I even checked in the ugx asset counter and the fx keeps resetting back to the original one... can someone please help?

Remove unused World at War weapons in the CSV's then rebuild it.
DLC3 uses around 390~ FX by default so there's barely any room for addition unless you remove some of the existing stuff.