Operating system: Windows-7-6.1.7601-SP1 64 Bits
Graphics card: GeForce GTX 770/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 430.64
Broken: version: 2.81 (sub 3), branch: master, commit date: 2019-08-26 20:39, hash: rBce2368cf69f5
Short description of error
If a bone has Connected enabled, it's location remains locked, even though it doesn't have a parent.
It's not immediately obvious that this is the reason why you can't move the bone.