We are working on a drama now and online editing stage, the editor pointed out that the clip we provided has some flickering showing.

The clips was shot with HPX with Canon HD lnes (w/o CAC) at 1080/30 setting on the cam and it was recording with AJ-HD1400 deck at 1080/60i.
Then we captured the footage from HD1400 to FCP with firewire, then back to HD1400. The timeline was set to 1080/60i to match the format on the tape.
Unfortunately, they had to use Avid DS Nitris for color correction, so they captured the video from the DVCPRO HD tape at 1920/1080 with AVID DS format I guess and then mastered it on HDCAM. Not that I wanted them to do that but that was the only way they can work.

Would this set up, unless it is synchronized, would it create field shit that resulting the flicker?

I'm looking into the workflow and one suspecious thing is that we had mastered the timeline on to AG-HD1400 at DVCPRO HD-LP instead of SP.

By looking at the manual, it did not mention LP being less quality, it seems to meant that LP mode is required to do longer recording same as "EX", so we chose LP. But I found out that SP records as long time length.

Can anyone clarify this? Does SP records better quality than LP as you find those modes in regular DV?