Of the 24 ordered, not all made it through E. coli cytoplasmic expression (Protocol/Expression and purification) to a clean, monomeric prep.
The ones that aggregated on SEC skewed toward higher computed surface hydrophobicity — consistent with what SolubleMPNN is supposed to guard against (PD-L1/Campaign/PDL1-R1/Run/MPNN-001), and the reason round 2 weights that term more heavily rather than treating it as a soft preference.