After parent bone with another bone, why my bones and mesh only visible in edit mode? No constrains I'm new to rigging, and there is my problem.
I followed the course called "The Art Of Effective Rigging In Blender", in the course, there is three bone system in one Armature, deform/target/control.

deform :  Directly bind with mesh.
target :  The target bones of "Copy Transforms" constrain added on deform bones.
control:  Control the target bones in world space, Where the problem appears. 

Problem: I parent the root bone of target bones to one control bone in edit mode, switch pose mode, everything disappeared (include target bones) but the control bones.
I followed the course all the way down, and compare the blend file with the blend file in course-files, didn't find any key different till now, I'll keep looking for it...
So if there is any solution or advice for this problem, thanks a lot!!

This is two blend files I uploaded to Dropbox
It seems like a Beta version problem, I rigged it in Blender version 2.83.
And I tried to rig it from scratch in version 2.82, It's completely no problem!