As I said, it is normal that the UC slack variables have positive values.
But concerning the dummy import flows, they will inevitably be zero if you have indeed bounded them to zero, and the solver finds a feasible solution. Should you insist that this is not the case, it would be interesting to see it. Could you then please provide a reproducible case?
Or, could you also post the full DD file (of the scenario you showed an extract), and the listing file, to see if there is something unusual?
But concerning the dummy import flows, they will inevitably be zero if you have indeed bounded them to zero, and the solver finds a feasible solution. Should you insist that this is not the case, it would be interesting to see it. Could you then please provide a reproducible case?
Or, could you also post the full DD file (of the scenario you showed an extract), and the listing file, to see if there is something unusual?