Drag & Drop Indexes are Working Wrong if Draggable Property Used

[onur-ozguzel]

Hi;

Thanks for this wonderful component.

Description

Drag & drop indexes are working wrong if draggable property used in ngx-sortablejs v3.1.4. (in v3.1.3 it' s working properly.)

How to reproduce

I uploaded a sample project at: https://codesandbox.io/s/dazzling-volhard-37sq5?file=/src/app/app.component.ts

Try to drag & drop Element 4 to Element 5. You' ll see that new order is generated like:

Element 1,2,4,3,5.
But it should be:
Element 1,2,3,5,4

I tested this on Angular 8,9,10.

If you downgrade ngx-sortablejs version to the v3.1.3, it' s working properly.