Difficulty with first 3D carve on detail passes

We would appreciate some insight if anyone has it!

Attempted our first 3D carve, created in VCarve Pro (a purchased file) and exported into Easel. The roughing pass went great, and the first detail pass started well but went almost and inch lower and taller than the original circle, almost like the file was stretched.
Assumed it was Easel, so tried UGS and had difficulty probing for Z so decided to purchase Picsender based on reviews. Roughing pass once again went great, but first detail pass went off the original circle this time as well as too deep.
Not sure what we might be missing here, or if we aren’t setting things up correctly after changing bits.

Did you re-probe to re-establish your z offset after changing bits?