In some prints and just some segments of the print some defects appear in the wall of the print. The strange thing is that only one side of the wall got the defects, in one side this waves appear and in the other it is perfectly smooth. The defects lines align perfectly with the layers.
It looks like your STL did not export properly from your CAD program. I suspect that the artifact is in the model rather than anything in the print process. Use the slicing tool on the right to see the tool path for the effected area.
Download NetFabb and run your model through the freeware function and tell us what it reports. There’s no way to say anything about what’s wrong based on your screengrab of PreForm. Need more details.
It looks to me like you may have had some non-planar polygons, which ended up wrinkled when Blender exported as STL. Blender (and many other CAD programs) allow polygons with more than 3 vertices, but those polygons have to be broken down in to 3 vertex polys for export as STL. Because of this, something that looks fin in the CAD program can look awful when exported.