Please clarify whether this is a power skip or a trim skip, (my terms). Meaning does it skip when you apply more power, or does it randomly skip, as if it wants to initiate a shift.

Mild power skipping is caused by unmatched pitches, or small burrs on a sprocket and tends to improve with breaking. Trim skipping is caused by things like poor trim, misaligned derailleur (bent hanger, or RD), and similar issues.

Often a system that ran fine before will begin to skip with new chain and cassette because the worn stuff was sloppy and forgiving and the new stuff isn't. Sometimes the chain was changed from one with nice bellmouth in the inner plates to one with less causing more sensitivity to slight trim error, especially with a new sprocket with sharp corners which are more prone to snagging.

Check the obvious, and if all seems OK, and the skipping isn't overly annoying, ride it a while and it may resolve with break in.