On the Timurid page there is custom JavaScript for handling the promotion, and I suspect the problem is in there. But it is already late now, so I will look at it tomorrow.
The morph method would probably allow promotion for every move that ends in the zone, also if it started inside of it.
Note that not even the succession would need custom script anymore; originally I used a custom routine BadZone to veto all moves where a King would swap with another pice than a Prince. But the captureMatrix can now do that too.
On the Timurid page there is custom JavaScript for handling the promotion, and I suspect the problem is in there. But it is already late now, so I will look at it tomorrow.
The morph method would probably allow promotion for every move that ends in the zone, also if it started inside of it.
Note that not even the succession would need custom script anymore; originally I used a custom routine BadZone to veto all moves where a King would swap with another pice than a Prince. But the captureMatrix can now do that too.