I have only ever heard of one instance of someone who had problems getting one and it was such a strange story behind it (green card on employment based visa but someone who wanted to work elsewhere, go figure, there were lawyers involved and the story sounded super strange, think the person doing the second hand retelling of it didn’t know the whole story.) other than that I have never heard of anyone having an issue or having their reasons questioned. The only thing is you have to be in the US both to file the application and to get biometrics done for it.