This could be a problem with collision.
- Open actor BP for actor you want to interact with
- Select the mesh you want to interact with
- Under ‘Collision’ set Collision Preset to ‘Custom’
- In ‘Trace Responses’ set ‘Visibility’ to Block.
If you just want your actor to collide with everything you could just set Collision to block all dynamic, but that may not work for your desired application. Once collision is set to block on the visibility channel your mouse over events should fire correctly within the blueprint.