Execution of drawDial() funcion in qstylehelper.cpp is interrupted in BEGIN_STYLE_PIXMAPCACHE() call.
Attached issue reproduces the issue. First there is no shadow in the QDial. After the first mouse click (so that the dialler moves) the outlook is the same, but after second click the shadow appears.
It seems that the execution in drawDial() is interrupted in BEGIN_STYLE_PIXMAPCACHE() so that the rest of drawDial() function is not executed, thus the shadow is not dropped though the state is enabled.