Wendy, FWIW I get the same thing. It's something to do, I am sure, with the Update from 462 to 470.
If I return BB to the old Build 462, the "Custom" tab works perfectly correctly and I can drag and drop from the full list of buttons that drops down. If I then come back to the latest 470, the "Custom" drop down is Empty.
I'm going to drop a note to Support.
Last edited by sixchannel; 11/22/17 02:20 AM.