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tokens: their subsequent dynamical mass-loss. This range represents an order of magnitude departure from the commonly adopted initial enriched fractions in MBL models. Figure 4. Required initial fraction of enriched stars as a function of the present cluster mass. Data points correspond to old () clusters born in high-pressure environments (), coloured by their gas pressure at birth. The grey area corresponds to the commonly assumed initial enriched fraction range of 5–10 per cent (Bastian Lardo 2018 ). The disparity between the commonly used range and our results indicates that either different polluters have to be considered (i.e. that produce greater amounts of ejected material per unit cluster mass, e.g. SMSs, see Gieles et al. 2018 ) or some yet-to-be-understood physical processes in stellar evolution and/or star formation lead to the large (>0.4) enriched fractions. 5 DISCUSSION We investigate whether dynamical mass-loss from GCs under realistic conditions satisfies the requirements from current multiple population models for reproducing the observed fractions of enriched stars in GCs. To do so, we use all surviving clusters present in the 25 present-day Milky Way mass galaxy simulations from the e-mosaics project (Kruijssen et al. 2018 ; Pfeffer et al. 2018 ). We determine the initial-to-present cluster mass ratios and study their dependence on cluster properties in Fig. 1 . We find a steep decrease of the amount of mass lost with present cluster mass. For intermediate mass (10 3 – M ⊙ ) clusters, we also find significant trends of increasing mass-loss towards smaller galactocentric radii, higher gas pressures at birth, and higher cluster metallicities. More massive clusters show no dependence between their median mass ratio and these quantities due to their small amount of mass lost. Assuming all dynamical mass-loss is in the form of unenriched stars, as posited by current multiple population models, we determine the enriched fraction of our stellar clusters. We study its dependence on cluster mass, metallicity, and galactocentric radius and compare it to observed enriched fractions from Milone et al. ( 2017 ) in Fig. 2 . These mirror the dependencies found for the amount of mass-loss and fall below the observed fractions by a factor of 2–20, with an opposite dependence on GC mass. These severe discrepancies rule out cluster mass-loss as the driving mechanism behind the high observed enriched fractions. In order to reconcile our results with observations, we consider what can be changed in models to match the observed enriched fractions. The addition of stellar evolution-driven expansion mass-loss, which is the preferred disruption mechanism suggested in the literature to solve the mass budget problem, predicts an even steeper trend between the numerical enriched fractions and galactocentric radius, in clear contrast with observations. These can only be reproduced if we consider an unphysically steep cluster mass-size relation, which