Missed your reply until just then, Hejden!
The thing that is supposed to be “blocked” by “should block on load” (or the SVB Blocking On Load function of Level Streaming Volumes) is the main thread. This is how it worked on UE3, and has been confirmed as being supposed to work on UE4.
So, basically - when you hit the Stream Level node, if block on load = true, what should happen is the entire game stops completely until the level is fully loaded and visible (if MakeVisibleAfterLoad) was checked. The reason these guys haven’t been able to repro it yet can only be that they aren’t streaming in a level large enough for the machine they’re testing on to take much time to load it.
Thanks for providing the Actor Initialization Time Limit tip - that should provide a better way for the Answerhub staff to repro it!
It’s worth noting that MakeVisibleAfterLoad also doesn’t work at the moment. The level is always made visible, which isn’t always what you want - sometimes you want to, e.g., start async loading a level in the background before you need it, so that by the time you want to make it visible it’s ready (and if it hasn’t already loaded, you do a blocking load). UE3 games, including Gears, did this all the time.
It’s been years since I reported this and it’s still like this, hopefully someone from Epic is still reading this thread and attempts to repro with a low ActorInitTimeLimit set.