MultiColumnListView Column list’s elements disappear when reordering the elements in the list

Steps to reproduce:

1. Create a new Unity project using the Universal 3D template
2. Open the UI Library (Right-click in the Hierarchy > UI Toolkit > Standard Elements > UI Library...)
3. Double click the "Multi Column List View"
4. Click the "Continue" button
5. Click the "Save" button
6. Select the "MultiColumnListView" in the Hierarchy
7. Open the "Columns" foldout in the Inspector
8. Add 4 elements to the Columns list
9. Click and drag the first element ("Element 0") to the bottom of the list all the way down
10. Click the closed foldout of "Element 3" (the one that is all the way at the bottom of the list)
11. Observe the Columns list

Actual results: Only 3 elements remain

Expected results: 4 elements are in the Columns list

Reproducible with versions: 6000.6.0f1, 6000.7.0a6

Can’t test with versions: 6000.0.0f1, 6000.0.82f1, 6000.3.23f1, 6000.5.11f1 (due to no UITK editing stage feature)

Tested on (OS): MacOS Silicon Tahoe 26.6.2