In the Raiser's Edge / Sphere Connector, transactions have come through during a sync. When attempting to open these up for processing, the window reads "Loading XX amount of transactions, please wait...". Once the window is open, no transactions appear.
These transactions may remain checked out by another user (e.g. due to a hung Citrix session or Raiser's Edge crash). If that user logs into Raiser's Edge now, transactions will load for him/her. Then, simply close the popup to release them for other users.