Going into a 24p sequence will yes, usually throw it out of sync you need/needed to take the odd man out (1080/30p) and re-encode it thorough fcp of compressor to get it to your main format (1080/24p), One show i did in the past had the same issue on on the D-camera and I had to re-encode that cameras footage through compressor to match the rest of the footage. So once you re-encode it then you will have the option to match frame your edits
-james