Deleting and re-posting the session containing new PBs does not appear to work. I tried it for a recent session (alpha PB) but deleting and reposting had no effect. What did work on that occasion was posting the new session then deleting the older session that contained the previous PB. This resulted in the new PB being correctly listed.
This workaround / hack isn't suitable in all scenarios though because there may be other PBs that you don't want to lose by deleting an old session.
Hopefully the tech guys will be able to remedy the issue.
p.s. There are also some duplicated results in the rankings. 250m in the UK is an example as #9 and #10 are the same session.