Maybe is index error in OB allocator shader.

[graphicboys]

In ObAllocateVert.shader 38 line (function allocChildTile):
This line:
"uint nextFreeAddress = (1U + 8U * nextFreeTile);"
Maybe error, I think the address do NOT need to plus one, so it's should be:
"uint nextFreeAddress = (0U + 8U * nextFreeTile);"
After I read your codes, I think the layout of node_next pool be like:
+------------------------+-----+
| Node at level0 | ....
+------------------------+-----+
"Node at level 0" contains 8 uint for address of 8 children.
Do you agree with me ?