Platform Browser mid section has a resizing cursor but can't be resized

How to reproduce:
1. Create a new Unity project
2. Go to File -> Build Profiles -> Add Build Profile
3. In the Platform Browser, hover on the section's separator near the scrollbar
4. Try to resize it

Expected results: The mid section can be resized
Actual results: The mid section can't be resized

Reproducible with: 6000.5.0a8
Not reproducible with: 6000.4.0b10, 6000.5.0a7
Can't test with: 6000.0.69f1, 6000.3.10f1 (Different style)

Reproducible on: macOS Tahoe 26 (M1)
Not reproducible on: No other environment tested

Note: Sometimes the cursor stays in the resizing state, sometimes it changes only briefly