When you have bees hanging on the front of the hive like that in warm weather, feeder in place, and entrance reducer set at the smallest setting you create a traffic jam for the foraging bees coming an going to the hive. You need to open the entrance to at least the next largest setting.
I do not use entrance feeders and the only place I use entrance reducers is for the top entrance/vent. I have bottomless hives and use the old reversable bottom boards for migratory tops.
If you hive absconded it sounds like they didn't like the digs. An overly hot (temp wise) hive (packge or swarm) will abscond if not settled in with brood.
Ways to correct an stuffy hive is through the use of slatted racks, vented tops, and/or screened bottom boards.