Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 550 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 376.54
Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-06-05 12:32, hash: rBa6cd77bad1c1
Worked: 02.06.2020 build hash: cecda64e2ead
Short description of error
In the latest versions, one of the bones in the attached file has disappeared.
This is because the object used to view it has become invisible.
File where the bug was identified:
Exact steps for others to reproduce the error
Open the bone_w_loose_edge_obj_bug.blend file in the latest master notice that FK_forearm.L is missing in pose mode and object mode.
Open the same file in the 02.06.2020 build and the bone should be there.
Simplified file revealing the bug: