If you are unable send your data, say activity items, from BQE CORE to QuickBooks Online, it could be because someone in your company enabled the option 'Do not send ... data' in the sync settings. You must un-check the relevant option (say 'Do not send activity data') under Integrations > Sync Settings to be able to send your CORE data to QuickBooks Online. The same applies to getting data from QuickBooks Online into CORE. Check CORE Help Center for details.