Less bulky development versions of the model showed an excessive propensity to reside in the center of the membrane. The large underlying atomistic SASA in the hydroxyl and aliphatic branching regions prompted the move to regular size beads there, instead of small. Counterintuitively, while this size change made cholesterol slightly more hydrophobic, it had a substantial impact in lowering the center plane population. This hints at the presence of a small space at the center of Martini 3 lipid membranes, likely due to insufficient interdigitation in the model or underestimated interactions between the terminal beads of each leaflet's acyl chains. As far as we know, no other reports on this have been made, but it is likely that other smaller molecules will also excessively accumulate in this region. Incidentally, the same inter-leaflet gap might already exist in Martini 2. Its influence, however, would have been mitigated by the fact that in Martini 2 interactions between small and regular size beads are the same as between regular ones.