if you try to change the default camera offset in the debug settings to a negative value (for example -6, to place the camera 6 meters behind the avatar), it will snap to 0.
it used to work in previous versions, but i am not sure in what version the bug first appeared.
setting the offset in the settings.xml and then not touching debug works, so it seems like only the debug settings have some bug.
appears to be bugged on windows and linux versions.
CPU: Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz (3997.7 MHz)
Memory: 16326 MB
OS Version: Microsoft Windows 7 64-bit Service Pack 1 (Build 7601)
Graphics Card Vendor: NVIDIA Corporation
Graphics Card: GeForce GTX 1070 Ti/PCIe/SSE2
Windows Graphics Driver Version: 26.21.0014.3615
OpenGL Version: 4.6.0 NVIDIA 436.15
RLV Version: RLV v2.8.0 / RLVa v1.4.10a