Here we have to distinguish between Skeletal Meshes which use the Unreal mannequin skeleton and Skeletal Meshes which have their own skeleton.

If you are using a character with a unique skeleton, you probably have to do much more than just the following points, regarding how much your skeleton differs from the unreal mannequin skeleton.

But if you are using a character with the unreal mannequin UE4 or UE5 skeleton you need to do the following steps

• Copy all needed sockets from the UE5 Mannequin skeleton to your custom character skeleton
• Create IK Rigs - One from the UE5 Mannequin skeletal mesh and one from your custom character skeletal mesh.
• Open both IK Rigs and do the following on both IK Rigs
• Open the IK Retargeter
• Create a new Animation Blueprint from your custom character skeletal mesh
• Open the new Animation Blueprint and add the following node
• Go to the Character Blueprint BP_DefaultCharacter and add a new skeletal mesh to the existing “Mesh”
• Now you should be good to go and your custom character is playing all the animations correctly.