Go into your send/receive settings “define send/receive groups”. Check your schedule automatic send/receive settings. Try changing it to more frequently. I believe the default is 30 minutes. If that doesn’t help try closing outlook and searching for your ost file and deleting it. Outlook will rebuild the ost when you restart outlook. It can take a while if your mailbox is extremely large, but a 100MB mailbox only takes a couple of minutes. If that doesn’t help try deleting your mail profile and creating a new one.