System Information
Operating system: macOS Sierra, Versión 10.12.6.
Graphics card: Intel Iris Graphics 6100 1536 MB.

Blender Version
Blender Version 2.81a (2.81a 2019-12-04)

Short description of error

Exact steps for others to reproduce the error

1. File, New, General.
2. Press A.
3. Press X, Delete.
4. Shift + A, Armature.
5. Shift + A, Mesh, Plane.
6. Press N, Transform, Rotation, 90º in X.
7. Press 1 (View Front).
8. Viewport, select Bone.
9. Panel Object Data Properties, Viewport Display:

9.1. Display As: Envelope.
9.2. In Front: Off.

10. Viewport, select Bone
11. Edit Mode.

Blender 2.79b

2.79b, Look at the image, everything is fine here.

Blender 2.81a

2.81a, Look at the picture, how it should look. Same Blender 2.79b.

View Front, no Ok.

OK

Observation:
Follow the steps.
Note: If you want you can activate Viewport, Shading, MatCap, select clay_brown.exr.