1080i50 video displays flashing lines on broadcast monitor

Hi,

I up-converted video from PAL SD to HD 1080i50 using Matrox MXO2 and Final Cut Pro. The video is clean but when I edit to tape and preview on the broadcast monitor attached to the Sony HDCAM VTR, the video has flashing lines across the screen. Some are end-to-end while some are just shorter horizontal lines.

Some things I tried but did not work:
- deinterlace
- uncheck the interlace setting in sequence settings
- change field dominance to none

Any ideas why or how to resolve this?