Per your company policy, if you did not try the new positions, are you supposed to go back to your old job?
One scenario could be that new positions do not work out and you will go back to your old position. Since you are not new to the department, you boss may be simply doing some preparation work for you to return and doesn't feel the need to get in touch with you until the end of your leave.
Or, it could be that some people are currently discussing about where to place you when you go back. In this case, they won't tell you anything (nothing to tell) until a decision is made. And if you will move to the new department, you should be notified by the new manager not your boss..
As you are in still in 產假 at the moment, I don't think they will contact you unless something important comes up. Does that make you feel like 老板給我個冷肩膀?
Just be patient and enjoy your stay at home for now. I would think some people may rather be left alone when they are in 產假 until the end.
