I have a seam in 'Shade Smooth' mode that I can't fix I am a bit of a novice when it comes to Blender and I'm having trouble fixing a very noticeable seam on a mirrored object (a head).
I've checked to see if there's vertices that haven't been merged near the seam to no such luck. I've changed the order of the modifiers (mirror and subdivision surface). &quot;Clipping&quot; and &quot;Merge&quot; are both enabled within the mirror modifier too. I've even copied and pasted one side of the head, flipped it and then tried to merge the vertices but that won't work either.

I hope this isn't a silly question, but I'm only a university student and would really appreciate the help!
Thank you! :)
Its caused by the subdivision modifier being used before the mirror modifier. Click and hold on the 6 dots by the top right of the modifier and drag the mirror modifier above the subdivision mod.
I am not 100% sure why having them in the wrong order makes that line appear, but changing the order fixed it for me. Also, it appears the line gets more pronounced the more subdivisions you have.