Cannot reproduce published data (level 4)

[khr97]

Dear CMap developers,
I'm following the pipeline and cannot reproduce level 4 data from the uploaded level 3 data.
In detail, I expected that within a plate the ZSPC values of a gene and inferred expression values of the gene would be plotted on a straight line, since median(X) and MAD(X) would be constant across a plate. However, I observed quite significant deviation of data points from trend line. Also, ZSPC values in uploaded level 4 data was different from the ZSPC values calculated manually by robust_zscore function.
How should I interpret this? Am I missing some points?