Element of the list disappear after saving (Demo 21)

[peterhorvathAV]

Short description
I ran one of the official demo of w2grid.: https://w2ui.com/web/demos/#/grid/21
I change a list element and press save. The changed element disappear

What is current behavior
The changed element disappear.

What is desired behavior
the changed element should be kept displayed

Link to jsfidle/codepan with sample code
demo on w2ui page:
https://w2ui.com/web/demos/#/grid/21

Steps to reproduce or sample

1. change an element in the list column
2. press save
   and the element disappear