Put the summary of the bug you're having here
1. join the world
2. create new scoreboard
3. quit this world
4. rejoin this world
5. Typing in /scoreboard objectives list found that all scoreboards be clear
What I expected to happen was...:
Describe what you thought should happen here
Exiting the world should not affect the scoreboard
What actually happened was...:
scoreboard be clear

Steps to Reproduce:
1. join the world
2. create new scoreboard
3. quit this world
4. rejoin this world