Check the map after each cycle of averaging. Don't do more than 3 to 5 cycles. It does not really matter if the solvent region is within the last cycle flattend or flipped. Before you start averaging kick the models to get different phases. Limit resolution to 3.0A or even lower and take all the data from 100 to 3 A with no cuts on sigma.
Higher terms like to convereg but to wrong phases.
You can try 3fo-2fc maps as well. By default FOBS maps are calculated. Use at least 2fo-fc. FOBS maps are not the best. The purpose of structure determination is NOT to get the R-value down, but to obtain better phase information to complete the structure determination.