It looks like possibly a combination of too high of extruder temperature and poor retraction.
In order to exclude a cooling issue, you could try printing a larger object alongside the spheres. Something that has a constant cross-section and is at least as high as the spheres.
I have had issues when printing objects with a sharp tip, even printing 8 at once the total amount printed on the top layers was not enough to let the material cool before the next layer.
It looks like it is trying to fill in what might be small gaps and is putting blobs down because the gaps to too small of a detail to accurately fill.