I have been having the same problem here. It seems random and in my case it gets stuck on the LG8FX board library. It also seems to get stuck sitting there on Processing when trying to install other libraries.
Given that people have reported multiple board libraries, it must be an issue with the latest release. I see someone has also logged this issue on GitHub.
I don't seem to have any problem when running 2.3.2, so I will keep running that version for now.