I went through my volume and picked a surface on my inline and crosslines using a 50 line spacing. I then tried to use 3D seeker plus to fill in the gaps and it did a good job on most lines. However, for a certain part of the volume it also picked the correct surface but with many random spikes downwards. What is weird is that it always returns to the proper horizon after. I used my existing picks as reference but otherwise left the defaults.

What am I doing wrong?