Hello,

I didn't customise files.
I only installed the ad manager plugin en and embeds plugin. But after deactivating I've got the same issue.

The strange thing is that I've got a staging copy of my site and there are no issues.

I played this evening with my forum in different browsers and it looks like the topic pagination isn't always loaded into the page and when this happens the page is cached and is looks if the pagination doesn't exist. No idea why this happens. I worked with firefox, no problem. I use chrome and sudden no pagination in a forum and after that also no pagination in that forum in firefox.

I'll keep testing.