Lots of people use CHDK on their SX60. Using playback mode seems to work for them. Leaves me at a loss to understand what's different in your setup.
FYI - CHDK overrides are done in the background and the Canon UI does not know they are active. So you need to check your images to see if they actually work. Also, you pretty much need to set Tv, Av, and Sv if you try to set any one of them.