timecode error


for years now i have this error in cubase. 6 / 6.5 / 7
maybe i do somehting wrong.
i have a video. frame rate and project are ok (25fps) i’m in 48/24
the movie is H264 mp4
when i drop the movie randomly and put timeline to start of the movie and use the “set timecode at current position” to 00:00:00:00 it’s not exactly 00 it’s what you see on the picture.

here i use the scissors tool with “snap” to seconds
and there’s a difference between the cursor position that should be 0:33:33:00 and the snaped second that is the vertical red line (33.32.21)
what is going wrong ?

to get this right it’s a bit tricky. i have to read the .21 that you see on the picture
then drop the movie to 00:00:00:21 ! then redoo the set timecode at position to 00:00:00:00
is it a known bug please ?
i try to write support but i have 2 other problems there and no answer for 2 weeks now …