Unexpected behavior: "warning: "the sum of goals must be 100%" considers only one Goal Plan.

Hi team,
in a performance document there are two Goal Plans: "Obiettivi Trasversali" (wights=65%) and "Performance Operativa" (empty).

After the Line Manager added a Goal in Goal Plan "Performance Operativa" (weight=35%) and submitted the performance document, the system displays the warning "The sum of weights for evaluation topic Obiettivi Trasversali must be 100%. The current sum of weights is 65."
Why does the system sum the weights only for one goal plan?

Following the configuration of the both Goal Plans:

How could I make the system "able" to provide the right sum, I mean considering the weights of the both Goal Plans?