Ink backs away from ink ball. This causes the print to become starved for ink

Ink is to short and buttery Add an ink varnish to improve ink flow characteristics. Talk with your ink manufacturer.
Ink is thixotropic Work the ink tray frequently to prevent gelling up.
Water is back building into the ink tray Too much free floating water. Check pH/conductivity and reset if necessary. Check ink/water balance to reduce the amount of free floating water.