I have on row one cell A1 = 3, E1=9, I1=4.
If in cell K1 I write: =CONCATENATE(A1:I1) I get 394
But if I try to sort the cells before concatenating them with =CONCATENATE(SORT(A1:I1)) I still get the same result. Why?
This is due to the principle of the SORT function, which sorts rows according to data in columns. It does not sort individual cells. The example in the link explains more.
If you want to get the result that you anticipate, transpose your data and place them: A1=3, A5=9, A9=4
and perform: =CONCATENATE(SORT(A1:A9, 1, TRUE)), which gives you 349.
Or if you need to stick with row, transpose the cells in between. Use your original cell configuration and perform: =CONCATENATE(SORT(TRANSPOSE(A1:I1), 1, TRUE))
Note: Those additional parameters are required according to the SORT function help, however it seems that 1 and TRUE are used by default if they are missing.