Blender Version
Broken: 2.79 to 2.90
Short description of error
Metaballs only work in the first scene. Except for linked scenes.
Exact steps for others to reproduce the error
Open default startup
Delete the cube
Add a metaball
New scene>full copy
The metaball will be invisible in the new scene and visible in the first.
Other way to reproduce the bug:
New file
delete cube
add metaball
New scene>new
add other metaball