I add a socket to my character in the skeleton tree, and then in the character blueprint, I attach a mesh like a weapon to it and adjust its rotation and position. Then I go to my animation blueprint, and the mesh that is using the socket is not in the preview of the animation blueprint. What works is that I can add a preview asset to the skeleton tree, and then it will be visible in the animation blueprint.
In the animation blueprint, is there really no way to preview the attached mesh to a socket in the character blueprint?
Hey @dabbbbbbbb5656!
So what I’m hearing, please correct me if I’m wrong, is:
When I add a mesh to the character blueprint and see it in the viewport, is there no way to make it automatically update the Animation Blueprint to match the character?
I don’t think there is. You see, the Animation Blueprint can be used across a wide array of characters, even ones with different skeletons, and is not tied to a specific blueprint. You can make Blueprint_A and BP_B and give them both the same skeletal mesh, which could use different ABP’s as well.
A Blueprint is a core to attach many things to and make them work together but those building blocks can be used for any other matching Blueprints, as well. So the problem lays in- if we make the ABP preview the Blueprint it’s attached to… how would it know which blueprint to use?
The only way to make it guaranteed update would be to update the skeletal mesh that the ABP is attached to. Then you would see the effects on both the Blueprint and the ABP constantly. Until then you just have to right click → attach preview mesh to line things up. 
Let me know if I can explain any further!