To reproduce:
1. Open project, load Scene, there should be a Main Camera with 4 GOs inside (A, B, C, D)
2. Open Custom->Open to show the editor window
3. Click Set As First, notice how it actually sets it as the last (index childCount-1)
4. Click Set As Last, notice how it actually sets it as the first (index 0)
Expected result: SetAsFirst/SetAsLast should set it as first/last
Actual result: SetAsFirst/SetAsLast sets it as the last/first