Sorry it's me getting confused then about the safe homing.
With regards to the printer already knowing it's above 13mm so drops down then extends kind of makes sense but I'm pretty sure that's not what mine does. Mine will always raise before it extends the probe even if it knows it's at z 100. I haven't printed anything close to my z max but if I did I would have to manually move the nozzle down to avoid it maxing out and crashing so it seems strange. I don't know enough about all this stuff yet but I assumed a homing command would erase the current location and would just look to hit an endstop. The exception being safe homing but that still needs to start from x0 y0 it doesn't use the current position to do a move. I'm probably just getting in the way so I apologise if this isn't helping. Roxy is definitely the one who knows what she's talking about so hopefully you guys will sort this thing out pretty quickly.