with the latest SVP version those nasty artifacts are gone even if motion vector grid is set to "small 2".
THANK YOU!!!!!!!!!!!

here below a clip with the same white residual artifact:

http://www.mediafire.com/?6040970a8pt0ll0

BTW, try this settings:

Thank you, AndreaMG.
It is serious bug. And it will be not simple to fix it. And not fast.

Now you can change Motion vector grid to 24 px. Large 2.
It is not ideal solution. But you will be able to watch video without annoying wave artifacts.
It is temporal solution. Until the real fix will be implemented.

Thanks Mag.

Playing other videos in fast scenes wave artifacts seem to be worst than before.
Here another sample (the ball and the legs are all messy, sure there is a lot going on screen and even some watermarks, but please notice the end of the scene where the man is climbing the stairs, the scene is not so fast moving, but the profile of his head is messed up by wave artifacts all the same):
http://www.mediafire.com/?mj6xtmas9t9b01i

If I run in another scene with the residual "white mask" problem I'll post it.

Apart from that when the scene is calm at times it seems to watch real 60fps content 

Now you can change Motion vector grid to 24 px. Large 2.
It is not ideal solution. But you will be able to watch video without annoying wave artifacts.
It is temporal solution. Until the real fix will be implemented.

Here is the sample:
http://www.mediafire.com/?dygotr4d00nd71r

See attached file for my settings.

have you done some changes in how the masks work? Yesterday I was playing a video in 720 at 23.976 to 60fps,  frame interpolation mode set to "uniform" as usual and I noticed some unusual wave artifacts, because they came with a residual white line (presumably a mask) along with them which was very distracting.