Unexpected behaviour when selecting items in UI Toolkits TreeView sample

Steps to reproduce:

1. Open a Unity Project
2. Open the UI Toolkit samples via Window > UI Toolkit > Samples
3. Select the 'ListView' sample
4. Click on the first option in the list (the number '1')
5. Observe how 'Items selected: 1' is logged to the console as expected
6. Select the 'TreeView' sample
7. Click on the first option in the list (the number '1')

Actual results: The text 'items selected: 0' is logged to the console. You have to click on the item a few times for the correct text 'items selected: 1' to start being logged.

Expected results: The text 'items selected: 1' is logged correctly the first time that the item is clicked

Reproducible with versions: 6000.1.0a5, 6000.0.28f1

Not reproducible with versions: - 

Can’t test with versions: 2022.3.52f1, 2021.3.45f1

Tested on (OS): MacOS Sonoma 14.6.1

Notes: 

• Issue only affects the TreeView sample. The ListView, MultiColumnListView and MultiColumnTreeView all log the correct numbers on the first time clicking an item
• The issue affects all the numbers on the TreeView sample (1 - 10)