2018 GMC Terrain Body & Structure Problems

The strike plate on my rear driver door fell off. The plate and bolts are in perfect condition but the backing is gone. Multiple body shops have attempted to locate the backing, which is somewhere between the interior and exterior metal body pieces, and gave been unable to. Every body shop I've taken it to also says that they have never seen anything like this happen before. They are reluctant to fix it because that would mean cutting through the body to replace the backing for the strike plate then welding, sanding, and painting in the area they cut and they worry about the integrity of the striker and functionality of it as well, as they've never had to do a repair like this before. One of the body shops was also a certified GM repair shop at the dealership from which the car was purchased and even they have said the same as the others. They also encouraged me to report this to the NHTSA and GM as well because they've never seen it happen or heard of it happening and they are concerned because it is a safety issue. I know that there is a similar recall on some newer GMC Terrains and wonder if my issue would be related to the recall or if it's is a separate issue all together. The striker was barely touched and someone exited my back seat and fell off into a parking lot, I was able to recover the striker and both bolts which are completely undamaged and unworn. This is my only vehicle so I now have to hold my door shut with bungee cords and tape in order to use my vehicle. I have a child who is still in a car seat and must remain in the back seat for safety but now my backseat is also not very safe because of the door. A few days prior to the striker falling off my door would not close fully flush with the rest of the vehicle but still closed, locked, and remained closed with no other issues.