Check the Send/Receive frequency settings.
Go to the Send/Receive tab, click Send/Receive Groups drop down menu, the click Define Send/Receive Group. Select the All Accounts group, unless you have setup a new group for your accounts, make the the option for Schedule an automatic send/receive every field is checked and adjust the time period if it's quite long. I usually set it for about 5 minutes. Click Close and see if this fixes the problem.

Let me know if this option was already enabled and what the setting was.