I'm not sure if this is exactly a bug, but it wasn't an issue on 8.0. The latest post in the Premium Name Changes thread before just now was mine on Friday at 11:40 AM/2:40 PM. However, @Plums couldn't find it while fulfilling requests. My post happened to make a new page (237), but it wasn't showing in the pagination in the forum or in the thread. However, it was showing that I made a post at the time mentioned above when viewing the Last Message column in the forum. Plums told me to re-post my request and now the last page appeared, so I'm not sure what's going on.
Definitely a strange issue. We had to do some rebuilds during the upgrade due to an update to our Post Macros add-on, which is what I imagine has caused it. I'll do some more research into it, it may be as simple as rebuilding again.
Didn't think this was worth a new thread. Noticed it through a lot of threads, but often one of the pages between two numbers (e.g. page 7 won't show display between 6 and 8) won't show and you have to click next/edit the url to get to it. Spoiler Page 365 isn't showing System: Windows 8.1 Browser: Firefox 38.0.5
Confirming that this is/was a style issue and not a problem that required any rebuilds. I've made some tweaks, checked a few threads and they appear okay, and therefore marked this as fixed. If anyone encounters the problem again, just post and I'll reopen this.