When the ruler dies the new ruler gets to be placed to the "capital" ie. one of the homeland territories (with the Turks it is Rum, I think). That means that suddenly some of the territories are far from the padisah and can rebel instantly.
I'm not 100% sure but I think they pop up in your most developed province. As a sultan is dying in Asia minor and the new one is crowned (or whatever you do to sultans) in france, could it simply be that your new sultan is too far from some of your provinces?

Also if your old sultan had good builder virtues and lots of influence from conquering all over the shop then there will be a loyalty drop anyway when the new guy takes over, nothing you can do about that except weather it and carry on building and conquering.