Summary: The edge instantiation problem is a hypothesized resistant problem for safety in advanced agent scenarios where, for most utility functions we might try to formalize or teach, the maximum of the agent's utility function will end up lying at an edge of the solution space that is a 'weird extreme' from our perspective.
Edge Instantiation is a resistant problem if it is (1) a pragmatically important problem for advanced agent scenarios and (2) a problem that resists most 'naive' attempts to correct it. The proposition is not that the Edge Instantiation Problem is unresolvable, but that it's real, doesn't have a simple answer, and resists most simple attempts to patch it.