When I run /data get entity @s the log should output several lines of player data, but it hides the remaining lines of the data command output. When rapid-clicking on the line to highlight all of it, it can be seen that the other lines are there, just hidden behind the lines that follow.

It is possible to get the whole paragraph of data to show by clicking check-boxes randomly, but as soon as the log is scrolled the lines condense again.