If you are on the left of the exact middle of the map, he will go the left toward you, and vise versa. Possibly try looking both ways when trying it.
It isn't easy to tell if the biome you are in is surface or not because of the walls behind the house, I suggest breaking all of that. Also, as it states in the wiki, "to get the Truffle to move in, there must be housing in a surface Mushroom Biome during hardmode." judging by the list you have provided you have done all of the things that are required. All that's left is to see if the house you built is even suitable for NPC's.
As it states under the NPC section of the wiki, a suitable housing has:
- Proper Lighting
- Enclosed frame composed of blocks, a door, and walls. (Size: About 5x12 blocks)
- 1 Flat Surface Item (Ex: Table, Dresser, Bathtub, Bookcase, Workbench, Piano)
- 1 Comfort Item (Ex: Chair, Throne, Bench, Sofa, Bed)
From the pictures you gave, the program might be mistaking your Surface biome as an underground one because of the excess grass walls or not enough lighting. Another thing might be the height of the room.
If nothing works, just have a little patience, NPC's sometimes take a while to move in. Also, just try to preoccupy yourself with something else while waiting to help pass the time. Another thing, those walls inside the house must be player placed, if they spawned that way (Which I doubt, but doesn't hurt to inform you) you need to remove them.
Please Note: that there is a bug where if you killed the boss Plantera before the Truffle moving in, he will not move in and you will need to make a new world
Best Answer
As per the wiki, Truffle requires a vacant house built in an above-ground surface mushroom biome before he will move in. The world also has to be in hardmode (i.e., the Wall of Flesh must be defeated).
A mushroom biome can be artifically created by collecting a bunch of mud and placing it wherever you want the biome to be. Then take some blue mushroom seeds (found in natural mushroom caves underground) and plant them in the mud you just placed. It might take some time, but after a while the mushroom grass will spread to the rest of the mud and the biome will be complete. You can tell when the biome is finished when the screen darkens near the area and the music changes.