The question of copyright comes up often in our little circle, & here are some observations I have made over the past several years.
Alot of people claim copyright for WW2 photographs, both private individuals as well as muesums/archives. In most cases, it is only a 'claim'. They really have no idea if they are the legal owner of copyright for a parituclar item.
For example, the Imperial War Museum claims copyright for all their captured German WW2 photos. The AKG claims it for theirs too. Those two archives often have the same photo; I guess someone is lying. Hans Wijers is a good example of an individual claiming copyright for everything that touches his fingers!
This seems to be a 'European' disease as the U.S. archives such as NARA or the LOC are very upfront about their rights (or lack of).
Regarding Nazi material, it is complicated. Some of it was declared to be 'public domain' and not applicable to copyright law. Some was not.
Each photo in question would cost an enormous sum of money to verify the legitimate copyright, which is why people & institutions simply 'claim it outright'. Their tactic is to scare you away. Fear is cheap.
So, don't be too scared when it comes to someone claiming copyright for an item going back to Nazi Germany, ESPECIALLY generated from a government employee.
The reason why copyright is so often extended in our lifetimes is to forever protect big corporate icons, such as 'Mickey Mouse', or blockbuster movies or books. Our hobby is not even close to that kind of financial interest. But unfortunately, it does have a negative impact on our ability to collect.
Remember, if someone accuses you of copyright infringement, it is up to them to prove their ownership in court. In most cases, it would be impossible.
It is sad that the general public has no idea whatsoever how they get screwed on this copyright legislation. Every 15 years or so, it is quietly extended, and nobody notices or complains. After the revolution, the founding fathers of the USA declared copyright to exist for 14 years.
Compare that with now.