Reproduction steps:
1. Open the “SortingIssue“ project
2. Open Memory Profiler
3. Select any snapshot
4. Open the “Unity Objects“ tab and observe the “Allocated Size” column

Expected result: Objects are sorted by “Allocated Size” (default sort order defined in UXML is provided on accessing it via API and can be applied on initial displaying of the MultiColumnTreeView)
Actual result: Objects are not sorted by “Allocated Size” even though the header shows that they are

Reproduced in: 2023.2.0a9, 2023.2.0a16
Not reproduced in: 2022.2.21f1, 2023.1.0b17, 2023.2.0a8
Could not test in: 2020.3.48f1, 2021.3.26f1 (Unity Objects feature not available)

Reproduced using: macOS 13.3.1 (Intel), Windows 11

Notes:
1. Memory Profiler fails to sort correctly because, on the initial building of the view, the Sort Columns that are set in the UXML file are not reported when queried
2. The regression seems to be in UI Toolkit, not Memory Profiler
3. Sorting becomes correct when clicking any header to resort