Bug introduced in V9 and fixed in V11
Same story as in NotebookImport ignoring multiple style cells,
CellPrint @ Cell["test", "Section", "Program"] Cells[CellStyle -> #] & /@ {"Section", "Program"} This cell was only found by "Section" selector. I'd expect "Program" to work too.
And again, multiple style cells are officially supported so I consider it bug.
