Certified GKH Gardening Expert
Most likely it is a watering issue. There may be a gap in the soil that is keeping the water from getting to the roots or just too little water. Flood the place where they are planted to make sure that the soil is all filled in and then make sure they are getting enough water after that. The non-blooming is likely caused by stress, probaly due to the watering issue. Additionally, you can try adding some more phosphorus, such as bone meal, to the soil around your plant.
Here is an article that you may find helpful: https://www.gardeningknowhow.com/ornamental/flowers/lantana/lantana-plants.htm