There are no special characters in these new LUTS.  For example, the LUT to convert FLog2C to Provia has a file name of: FLog2C_to_Provia_65grid_V100.cube Which special character are you referring to? I even removed the underscores.  That changes nothing.  I also placed a CST node in front of the LUT where I changed the output gamma to CineonLog. Again, no change. Don

I told you the solution. Rename the LUT without special character

Do you have the URL for that forum where there was a solution? Don

I found the solution on an other forum. You have to change the name of the LUT. The problem come from "—" caracter or I don’t remember wich on 

Hello, Delighted that you posted this as I too am having issues.  I own an X-H2S shooting in FLog2C.  I have tried a myriad of combinations of CSTs (with and without using CineonLog) and color management settings to get these FujiFilm LUTS to work.   As yet, I am yet to be successful. There must be a gap somewhere in my understanding.  Hopefully someone can help us out. Don