My comment is based on some articles from years ago about Germany and maybe other countries having trouble getting their gold back from the US. Googling a bit now results in a couple of articles that say that Germany did eventually get their gold back, but there were some hiccups and delays that made people wonder whether the gold was even there at all.

https://bmg-group.com/germanys-gold-reserves-u-s-paper-claim...

https://www.rt.com/business/445133-germany-access-gold-us-fe...

https://www.kitco.com/news/2017-08-24/Germany-Gets-Its-Gold-...

Turns out everything is fine, but a couple of years ago, people were worried about this. It looks like only Germany was involved and no other countries.

There was major foot-dragging when Germany wanted its gold back. Leading to the obvious conclusion that the gold wasn't there at all, and Germany was just holding worthless paper that did nothing more than point to a line entry in an account book somewhere.

> “Why would it take 7 years, unless there was a possible issue in getting it together, to return 300 tons? It could be done certainly in several weeks or even months – but 7 years?” Lanci questioned. “In my trading days, I’ve taken delivery of gold and silver and I’m aware of the physical logistical limitations. The time requested to deliver the 300 tonnes seems excessive – whether it be 5 or 7 years.”