[Jeffrey Carter] “I know the C100 (Mark I) does not record true 24p (23.976) but interprets the file. In the past, when I selected 24p, either Premiere or FCPX would recognize the file as 24p (23.976) and everything would be fine. Now, even thought the camera is set as 24p, PP and FCPX say the file is 29.97. “
The C100 does record true 24p (23.976). Are you setting the C100 to record 24p or 24PF? If you record 24PF you have to enable 3:2 pulldown to make it true 24p. You should never ever ever record 24PF.