Picture does not show the drain, so confirm no Ice in drain. I have a pot steamer, that I run through those drains,
If drain is not blocked, then make sure the evaporator is pushed all the way back and secured. There has been several post post o this same problem and I am going out on a call this week.
The drain trough check make sure it is curved up and toward the front. I like to set up these refrigerators with a slight tilt backwards, not level. Helps drain and door closing.
You may want to get some Permagum rope calk sealer, and make a dam on the front trough (trawf) see if that eliminates the problem.
the only other possibility is out side air causing humidity, excessive door open, door seal, Water tube for Ice maker on back not sealed.