DropDownTree input field does not show selected items correctly.

[martintabakov]

Bug report

The DropDownTree with remote dataSource and checkboxes does not show all selected values in the input field.

Reproduction of the problem

1. Open this Dojo example - https://dojo.telerik.com/@sspasova/umiNUfUR
2. The label in the input field shows 1 item(s) selected, although 3 items are checked. Similar to DropDownTree with checkboxes does not set value correctly #4411.

Current behavior

The label in the input field wrongly shows that 1 item is selected.

Expected/desired behavior

The label should display that 3 items are selected.

Environment

• Kendo UI version: 2023.3.1114
• Browser: [all]

[IvanDanchev]

Another example: https://dojo.telerik.com/aLacAxUB

1. Select some items and click outside the dropdown to close it
2. Click "Change data source"
   The tag displays the previous number of checked items