How to reproduce
1. Open the attached “PB_multiple_edge_issues” project
2. Open the “SampleScene”
3. In the Hierarchy, select the “test” GameObject
4. In the Tools overlay, click the tool context button, to swap into ProBuilder context
5. Select Edge Selection edit mode
6. Drag select multiple edges while holding down cmd/shift
7. Click on one of the selected edges while holding down shift
8. Observe the clicked edge

Expected result: The edge was unselected
Actual result: The edge remains selected

Reproducible with: 5.0.4 (2023.1.0a1), 6.0.7 (6000.0.57f1, 6000.2.3f1, 6000.3.0b1)

Reproducible on: macOS 15.6.1 (M1)
Not reproducible on: No other environments tested

Notes:
- The issue does not reproduce if holding down cmd instead, in step 7
- Edges require multiple clicks to unselect (2+)
- Faces and vertexes requires two clicks to unselect