It might be necessary to click the mouse to get it to reconnect after changing batteries.
That has always been the case with my 2014 iMac and bluetooth mouse.
That has always been the case with my Mac 10,6,8 too. It should be noted that the document is now archived which means it would not get updated as newer HT4294 is now the version. However, this too does not mention a click so why not send your observations to feedback ... but be aware, feedback comments are never acknowledged.
This article fails to note that it might be necessary to click the mouse to get it to reconnect after changing batteries.
