Body enter could be the problem.
If you want to detect collisions (rigid body has disabled contact reporting by default), use the RigidBody methods instead of body enter.
Not sure but I think that Kinematic nor static will ever "enter" a rigid on the same layer/mask pair (I could be wrong).
Also, if you want the bullet to keep moving pushing the rigid, it can't use move() because it prevents overlaps, you will have to use set_pos.
If you want the bullet to pierce the body, you may need to work with areas on that layer instead of a physicsbody (be area on the bullet or in the player or both).
You can make objects with different combinations of areas and bodies (and layers and masks) to get many levels of collisions and detections to be reported to the main node.