A user informed me that utf8-plain (for XeTeX) doesn't work because \inputenc is called (which is exactly what utf8-plain shouldn't do).
It turned out that we use the wrong encoding check (the one of the document language's default encoding, not the actual selected encoding), which breaks LaTeX export as soon as a specific encoding is selected in Document->Language. This is actually my fault. I wonder why we didn't stumble across this earlier. This oneline fixes it. OK to commit? Jürgen
Index: src/BufferParams.cpp =================================================================== --- src/BufferParams.cpp (Revision 19162) +++ src/BufferParams.cpp (Arbeitskopie) @@ -1411,7 +1411,7 @@ texrow.newline(); } } else if (inputenc != "default") { - switch (language->encoding()->package()) { + switch (encoding().package()) { case Encoding::none: break; case Encoding::inputenc: