When a fence gate with block state in_wall=true is placed in the world by command, the fence gate refuses to change out of the in_wall=true state no matter how much it is updated, and will only update the block state once the player leaves and rejoins the world.

To test: /setblock ~ ~ ~ fence_gate in_wall=true

Then try to update it by placing blocks and cobble walls next to it and opening it and updating in any way possible. It will not update. Leave the world and rejoin to see the fence gate now updates correctly.