The new SCAN Operator: Process Mining in Azure Data Explorer

With the following test I would like to better understand the scan operator.

range i from 0 to 4 step 1
| scan with_match_id=matchId declare (s: long, n: long=0) with 
(
    step s1: i % 2 == 0 => s=1, n=s1.n + 1;
    step s2: true => s=2, n=s2.n + 1;
    step s3: true => s=3, n=s3.n + 1;
)

Why is s3 match 0 still active after s1 starts match 1?
Why is s3.n equal to 3 (expected is 1) at i 4 match 1?