I have some things you might try. First, make sure your camera is centered on the CameraBoom exactly like it is in the ThirdPersonCharacterBP. Second, there’s an option under Project Settings>Engine>General Settings>Near Clip Plane. Changing this value might help. From what I know, you may need to restart your project each time you change this value (in your case, lowering the value).
Here’s a video explaining more on that: https://www.youtube.com/watch?v=oO79qxNnOfU
Hope that helps!