Reproduction steps:
1. Create a new project
2. Create a 3D GameObject (e.g. Plane)
3. Add Cloth Component in the Inspector (Add Component > Physics > Cloth)
4. Click on the "Edit cloth constraints" button in Cloth Component to open Cloth Constraints Overlay
5. Switch to “Paint” mode
6. Paint particles by clicking or dragging on them

Actual result: No particles are painted
Expected result: Particles are painted

Reproducible with: 6000.3.0b2, 6000.3.0f1, 6000.4.0a5, 6000.5.0a1
Not reproducible with: 2022.3.69f1, 6000.0.62f1, 6000.2.13f1, 6000.3.0b1 (0470b869db67)

Reproduced on: Windows 11, macOS Tahoe 26.1 (M4)