In paring down the file so there are only two elements (both Lines). I see some unexpected things via the Element Info dialog:
1) On the element that is NOT showing the EC Data, I have two linkages (one for a line style and a second one for internal use). The Line element that IS showing the EC data also has a line style, but there is no line style linkage on it! Yet it shows in Element Info, the line style...
2) The "Handler ID" for the XAttribute linkage is slightly different between the two (which *may* be the crux of the issue). For the one the shows the EC Data, I see
HandlerID 0x56ff0000, ID 0x00001, bytes 242
and for the one that does NOT show the EC Data:
HandlerID 0x56ff0001, ID 0x00001, bytes 253 (HandlerID is slightly different... as is the size...)
Bruce