My parent blueprint had 4 child actors, all of the same class, which varied only by color and size. One of these child actor components was the offender, so after removing it from the parent class, the project is working again. There was nothing unique about that one child actor component, so I’m stumped as to why it was causing an issue when the others weren’t.
Similar to others, the project was working perfectly and saved normally, but upon reopening is when everything crashed.
For now, until we understand why this happened, I’m not going to risk it again, so I’ve deleted all the child actors from this parent BP and placed them into world, as Bioluminescence did. It’s not a permanent fix, but few things scare me so deeply as not being able to open my project in the morning.