SceneManager.LoadScene Crash in 5.4.1

Not sure if this has been addressed, but I lost an entire day yesterday trying to figure out what's going on and searched far and wide on the internet about this issue to no avail.

I am upgrading from 5.3.4f1, where my project has one or two scenes that switch with one another during game, one of them being a terrain that's heavily decorated with rocks (I'd say among the thousands, I know I should optimize) and trees.

5.3.4f1 would switch just fine between them; calling "SceneManager.LoadScene("Name") as additive and waiting for activation would work all the time. As soon as I upgraded to 5.4.1 (and earlier this summer to a previous version of 5.4.x) the editor crashes entirely when it reaches that chunk of code and brings up an error report window, and worst: sometimes it does not crash at all and does what it should.

I thought it was due to a thread race condition and thus moved the LoadScene code to a part of the script execution loop that I believed would not generate any thread race conditions (such as a FixedUpdate on a script forced to run last on the priority list) but it still happens.

I believe there is a problem related to de-activation of scripts when switching to a different scene, since the same crash happens when I hide very large hierarchies of game objects: for instance, my scenes have every game object parented to a master game object that can be hidden on specific situations: trying so in 5.4.1 will crash the editor.

I need to keep this way of working as I need to switch from a scene to the other quickly for cinematic culling reasons, so please don't start suggesting "why don't you do it thiiss other waayyyy...."; I'm bringing up something that worked perfectly fine in 5.3.4f1 and is now broken entirely in 5.4.1.

I'm not really reporting this as an issue yet, as maybe I am missing how scenes are switched and disabled on newer versions; I'd like to discuss that here.

 

Will take me a while to package a project with the isolated issue, but for the sake of having this solved I guess I should invest another day on this just to file the report.

 

I'm having the same issue, though it still happens when I switch back to Application.loadLevel. It's not even in a loop or anything, and I've commented out every possible other line at that point during the execution, though it's possible the computer I'm using it on makes a difference in whether or not it happens. Are there some unwritten rules about where you can or can't (or shouldn't) try to load new scenes?

 

The best you can do is send these guys a crash report. I am right now dealing with a similar issue that only happens in the stand-alone player; the game crashes when it tries to delete some objects, specially those having disabled colliders after a scene has changed multiple times. If this stuff keeps happening, I will just switch back to 5.3.1 and screw this madness, it's only making me waste time.

 

The number is 853512, I believe. Just submitted a brand new one using the latest engine version.