During tanking, engineers spent several hours troubleshooting a liquid hydrogen leak in an interface used to route the cryogenic propellant into the rocket's core stage, putting them behind in the countdown. Attempts to resolve the issue involved stopping the flow of liquid hydrogen into the core stage, allowing the interface to warm up for the seals to reseat, and adjusting the flow of the propellant.
Teams successfully filled all tanks in both the core stage and interim cryogenic propulsion stage before a team of five was sent to the launch pad to finish Orion closeout operations. Engineers conducted a first run at terminal countdown operations during the test, counting down to approximately 5 minutes left in the countdown, before the ground launch sequencer automatically stopped the countdown due to a spike in the liquid hydrogen leak rate.