Tie forces break but slur does not
I'm transcribing a piano concerto where there are tied notes in the orchestra part (in this case, it's a piano reduction of the orchestra part).
Here is the section in question (measure 1) with ties:
I tried it with slurs instead:
The tied notes seem to take up more space than the slurred ones for some reason. However, what's more concerning to me is that it's able to force the staff to break to the next line even though there are significantly less notes than the piano part above it. I've tried decreasing/increasing stretch, but that doesn't seem to help. Could anyone help me remove the break or at least explain to me why this is the case?