https://www.kenstone.net/fcp_homepage/24p_in_FCP_nattress.html explains all.
NTSC DV is always 29.97fps no matter what! If you tell FCP to capture at 23.98fps, it will, but because the tape is not at that speed, it will just randomly drop frames.
If you shot in 24p Advance, capture as 29.97 with the advanced pulldown removal function, and FCP will remove the correctly falgged frames to give you true 24p.
If you shot in 24p 3:2 pulldown, then just capture as normal NTSC.
Don’t whatever you do set FCP to capture with a 24p timebase or it will mangle your footage.
Graeme
– http://www.nattress.com – Film Effects and Standards Conversion for FCP