Hmm? You can try chucking the plug in a drill and spinning the cavity on a cone shaped piece of 200-400 grit paper to smooth the inside surface. Looks like a super close fit of plug on ogive and a turning ridge on the contact surface may be “grabbing” the bullet. Also there should be enough neck tension to prevent pulling the bullet back out of the neck once seated. Other than that... got me?
It is. It looked to me from the inside of the neck that it had gone into the case and was just pulled right out. Told my dad it seems with me, nothing is ever just plug and play. Same reason I don’t ever attempt DIY projects around the house.