Hi @Tsam ,
Based on my test, Concatenate labels work well when there is no sort (which causes an implicit sort correctly), or sort by the x-axis:
This is due to a default sort that gets applied in one of the creation paths.
So in summary, I think it's impossible to sort by value again after the Concatenate labels option has been enabled.
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.