Disappearance of seat belt buckle

Hello,

I have had a Hyundai Tucson 2023 for a few months.

Yesterday, I noticed that the seat belt buckle (metallic bit) in the back seat seems to have disappeared. It may have gone into the seat belt retractor housing in the boot but I cannot get it back. I opened the hatch of the side of the box in the boot but I cannot see it. I cannot see it through the front slot either.

Do you know how I can get it back? Can I do it myself or should I go to Hyundai center?

Has anyone had this problem before?