First I have two comments, unrelated to your question.
1) I expected you would have an independent variable for the vertical location of the hole such as hvp.
h1 = r + hvp*(H - 2*r)/100
When you use hlp, the hole is always going to be on the diagonal of the block. When you use hlp and hvp, the hole can be anywhere on the face of the block within the margins.
2) SpaceClaim does something weird after moving d1 to 15. Look at this sequence of events.
See how after the move, SC has repositioned the marker for the face? This is because the top surface went from having 3 faces to 2 faces. You changed the topology. Don't do that. When you set d1 back to a larger number, a third face is created, but it disturbs the marker. Maybe this is a bug. I don't know.
You can avoid that by not allowing fcp to go to 0 or 100. Make the limits 1 and 99 or smaller. However, this is not your question.
Now to answer your question with a question. Do you understand how SpaceClaim updates geometry with Parameter inputs?
Here is what happens when the geometry goes from DP 0 to DP 10, a surface is created and Mechanical doesn't know its thickness.
It's like when the parameter pushed the hole outside the block, things in the geometry model were broken.
I find parameter updates much more robust in DesignModeler because it is a history-based modeler, while SpaceClaim is not. However, I recall that model history was added as a feature to a recent release of SpaceClaim, I have not yet looked into that.