The bug

When an objective is set to display in a colored sidebar such as sidebar.team.gray or sidebar.team.red it is not visible from a team with that color. The primary sidebar slot behaves as normal.

How to reproduce

/team add red
/team option red color red
/team join red
/scoreboard objectives add foobar dummy
/scoreboard players set @s foobar 100
/scoreboard objectives setdisplay sidebar.team.red foobar

Observe that your score of 100 does not show up on a sidebar to the right side of the screen.

The command does complete successfully, however, and returns "Nothing changed, that display slot is already showing that objective" if the objective was already in the slot when you ran the above command.

/scoreboard objectives setdisplay sidebar foobar

Observe that your score of 100 does show up on a sidebar to the right side of the screen.

Note:

This happens in a fresh world and does not appear to be related to MC-123104.