I have done a bit of research and other forums have had the same issue since the upgrade. It appears there was an administration setting that never worked in PHPBB3 and since the update they fixed the option, however because the option wasn't defaulted on the update, each individual thread needed to have this option enabled. Have you seen how many threads there are? Well anyway reading through the support panel someone wrote a database query which allowed me to update every thread automatically by simply submitting a single line of code to the database.
The problem should be now resolved, fuck im glad theres cunts out there that are smarter than me

Let me know if your having further issues.
Cheers