Strange interpolation with natual-neighbor metod

I have base shape file and try to use different interpolation methods to get image like this:

This layer is constructed using point to raster conversion.

Generally, interpolation methods as idw and so on works normal, but exactly natural neighbor does very strange thing:

Result is veeeeery long image. What can it be?

P.S. 180th meridian goes through my map, may it be reason?