How to reproduce:
1. Open project "Transition Issue.zip"
2. Open Menu > Window > TwoPaneSplitViewIssue Window
3. Resize the yellow pane by dragging the bottom bar down
4. Press the "Hide split view" button
5. Press the "Show split view. Notice pane has reset size" button
6. Observe the yellow pane size
Expected result: Yellow pane size is the same as after the 3rd step
Actual result: Yellow pane size is changed to the primary/minimum size
Reproducible with: 1.0.0-preview.11 (2020.3.35f1), 1.0.0 (2021.3.3f1, 2022.1.1f1, 2022.2.0a13)
Could not test with: 2019.4.39f1 (No UI Toolkit package), 1.0.0-preview.9 (Blank "TwoPaneSplitViewIssue" window)