SharePoint Approval process not working

I have a user who is in an owners group on his SharePoint and he no longer can approve/deny versions of documents. There is nothing extra added to the libraries and he is the only user who cannot approve documents. I have tried removing him completely from the site and readding him and giving him site admin permissions. Are there any other steps to try to remedy this?

The document library is massive with over 100,000 items. I think this could be the reason as the site owners just put random folders everywhere but again this one user is the only one with the issue.