I'm writing my Masters thesis and I'm cross-referencing figures a lot. The reference seems to work initially but then later on I'll go back and see the "Error, reference source not found" error. This happens on sections that I'm finished with and don't even touch anymore. It also happens when I cross-reference and endnote (though the numbers relating the endnotes themselves are fine). I can't see why this is happening. I'm just writing sections and using CTRL+A and F9 to update the table of contents and table of figures.