Bad news: I’ve already reverted my project and attempted to fix it on my own, so it is no longer in the same state as it was when I initially sent this message.
Good news: my attempts to fix it actually did end up fixing it. The problem (if I recall correctly now), was that one of the interface functions had been modified causing pins to automatically unhook from a call to that modified interface function in a class’s event graph. These unhooked pins were keeping that class from compiling and that class was being used extensively in the project (so other items were attempting to reference the uncompilable class. When I hooked up the pin, recompiled the asset, and then did the same stuff that was originally causing the editor to crash on load, everything loaded up fine.
Bad news: this is only one of many situations I have encountered over the past two months of trying to do Blueprint-only programming where some action I take causes an asset elsewhere to suddenly unhook pins and / or require recompilation. This then causes a chain reaction in other assets that reference the asset that can’t be compiled which results in the editor crashing. Sometimes the engine crashes when I attempt to save, other times compile, other times, (like this time), when I try to load the engine. It is by far the biggest bug I have come across.
I already have a feature request setup (something like Notification of Necessary Attention or something) that would seriously help to prevent these sorts of problems.
I don’t have an explicit case to share with you sadly. I will certainly try to show you some screenshots of my Blueprint setup tomorrow though.