Assuming your operators are not radically adjusting the ink on press and that your ink supplier is supplying the correct formulation to suit your anilox, plates and substrate you may need to look at your driers. Maintaining the right velocity, balance and direction of air between decks is critical if it is not to end up being directed onto the plate cylinder, which will cause the ink to dry on the plate.
Driers can become easily blocked over time with ink, and substrates and dampers may be adjusted during regular maintenance and not correctly reset. You can check the velocity of the air from your driers and this should be routinely checked to ensure it complies with the manufacturer’s recommendations.
You did not mention if this was common on all decks or just one or more. If it appears to be on only a few of the decks then it is almost certainly more of a mechanical issue, i.e. dampers opened to wide, angled incorrectly, improperly balanced, or some sort of blockage could be causing air to be deflected onto the cylinder or cylinders causing the premature drying of the ink on your plates.
Also, double check that one or more operators are not putting additives into the ink to help speed up drying. This can and will also contribute to ink drying on the plate if carried out to any excess. If this is the case you need to start with fresh ink as any used stock may be contaminated and will continue to cause the same problem.