This hotfix addresses an issue with Multi-Category schedules not including elements from linked file.
Make sure that Update Release 3 has been applied prior to adding the hotfix.
Verify that the build number of Revit 2015 within the Help > About dialog is 20140606_1530.
The Readme contains the latest information regarding the installation and use of this update. It is strongly recommended that you read the entire document before you apply the update to your product. For your reference, you should save the Readme to your hard drive or print a copy.
http://knowledge.autodesk.com/support/revit-products/downloads/caas/downloads/content/hotfix-for-aut...