I’m really happy that you are looking into this, but I also have to make clear that users experience this differently.
We do NOT get the freeze in the MainMenu in our project.
We get it in the GameLevel, after connecting to our DedicatedServer. And we can simply sit in the lobby, without changing any Widget and it’ll freeze eventually.
Also another user in this question explained that they went through removing all widgets and it still froze. So I don’t direclty believe it’s only widget related.
And even if it is, then it’s deep in the engine.
We were actually able to reproduce the issue in Allar’s Generic Shooter, who also answered with “Somewhere deep down in the Engine.” We would really need someone from the Engine devs on this who can properly look into the low-level thread handling. Our project constantly shows the libOPUS library and DX11 when freezing and making a dump file.