Reproduction steps:
1. Open the attached “BugRepro” project
2. Make sure that the memory breakdown is enabled (Edit > Preferences > Memory Profiler > Show reserved memory breakdown)
3. Enter the Play Mode
4. Open the Memory Profiler window (Window > Analysis > Memory Profiler)
5. Click the “Capture New Snapshot” button in the Memory Profiler window
6. Open the snapshot within the Memory Profiler window
7. Navigate to the "All of Memory" tab
8. Expand the "Managed" foldout
9. Observe the Reserved memory section

Expected result: The Reserved memory section displays a detailed breakdown
Actual result: The Reserved memory section shows no detailed breakdown

Reproducible with: 1.1.6 (6000.0.55f1, 6000.1.15f1, 6000.2.0b11, 6000.3.0a4)

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

Note: Link to the discussions [https://discussions.unity.com/t/reserved-memory-breakdown-in-memory-profiler/1667046]
As clarified by MartinTilo in that discussion, the option does not affect reerved managed memory but only reserved native memory.