Ajax Pgination Not Working (On Old Posts)

Hello,

I recently moved a site from one server to another, and, since the move, on any post that had ajax/paginated comments.. when you click the "load more" button, the button disappears, but, new comments to not load. The ajax response returns something like:

{"success":true,"data":{"is_show_load_more":false,"last_parent_id":"351","comment_list":false,"loadLastCommentId":351,"callbackFunctions":[]}}

It's not getting a comment_list back, even though they are more comments.

On any new post after/comments that have been created after the move, the load more works fine. Is this a known issue/is there any way to fix this for the old posts? I also tried switching to the wpdiscuz ajax (instead of wp ajax) and I had the same results.

Note: This site has no caching plugins, it's also a private site so I can't really provide a URL that you will be able to view.