The current version of LyX-gc uses the '»' and '«' UTF symbols to mark where the error occurs in the ChKTeX style output. Since round beginning of April, 1.5.0svn stops parsing the ChKTeX input once it reaches such these non-ASCII symbols.
I don't know whether this is bug. It is easy to work around on the LyX-GC side by replacing '»' and '«' with the slightly less pretty ">>" and "<<" ASCII equivalents. -- John C. McCabe-Dansted PhD Student University of Western Australia