Was that always the case with your installation of windows or is it new?
Did you install a custom codec once?
I read somewhere that windows updates can screw those up and they need to be reinstalled.
I have issues with my LX100 raws, which do not seem to be supported by windows Panasonic RW2 support?
Trying to find a solution, I came across this custom codec: Panasonic RW2 support?
Maybe it could help to solve your problem too, although I still hesitate to try it out.
Have you heard anything about it yet?