Reproduction steps:
1. Open the attached “BugRepro” project
2. Open the “Assets/Scenes/SampleScene.unity“ Scene
3. Make sure that Compatibility Mode is disabled (Edit > Project Settings > Graphics > Render Graph > Compatibility Mode (Render Graph Disabled)
4. Enter the Play Mode
5. Observe the Game view

Expected result: Script reads back ComputeBuffer values: 1=24, 2=24, 3=6
Actual result: Script reads back zeros for all values: 1=0, 2=0, 3=0

Reproducible with: 6000.0.58f1, 6000.2.6f1, 6000.3.0b3, 6000.4.0a1

Reproducible on: Windows 11
Not reproducible on: No other environment tested

Note: Not reproducible when “Compatibility Mode (Render Graph Disabled)” is enabled