I just installed a new rear cog on my fixed gear, and now it is making this clicking noise. Is this a chain line issue?

I do not think this it is a chain tensioning issue because I tried loosening the chain entirely and I still get the same clicking. I do not think it's a bearing issue because if I spin the wheel without the chain it's silent. My guess is a chain line issue, but it looks fairly straight to me (maybe slightly off). Thoughts? If it is a chain line issue, what would the best solution be here?