The bug was caused by a static mesh (gold, to be exact) that was spawned from the same chest as the skeletal meshes. I’m not a 100% sure, but something happened to it during physics simulation, and it went through the landscape, and upon toggling physics off, it crashed the game. And mind you, it still only crashes the game for the client in a packaged game - never the server.
I still don’t know what causes this, but I’m marking it as solved for follow up purposes.