Weird Shadow Chunks

Hey all! I just finished reading the FAQs and I think this was mentioned in it, though it mentioned every LOD chunk being shadowed. The fix it suggested is that I remove/tweak one of my "lightmap" mods, but I feel like that might not totally be the issue here, since it works well except for this boundary.
Yes, I have a shader on, but the problem is still there even with the shaders disabled.