The 4rth load step is just the sum of the previous load step (from 1 to 3rd , where different loading condition has been applied).
Inside the static structural tree I wrote the following APDL command:
And inside the solution tree I wrote:

And all this APDL code work very well to get force reaction and moment reaction, that are boundary condition:
As you can see I get in the 4rth load step the sum of the previous load steps.
But, the same code doesn't work for the Joint probe
As you can see I get a row of zeros.
The solution can be found for each load steps (the first load step is zero because I didn't put any load) , see results for 2nd and 3rd load steps, so, the issue could be on the APDL code and it have nothing to do on boundary condition or joint node. Maybe to store joint forces and moments I have to write other APDL code?