The glitch prohibited NASA from securely putting liquid propellant into the rocket, thus the vital test was postponed while the problem was resolved. It had intended to resume the test on April 9th in order to accommodate Axiom Space's historic Ax-1 mission, but it announced today that it will be postponed until the beginning of next week.
“Due to the changes in loading procedures required for the modified test, wet dress rehearsal testing is slated to resume with call to stations on Tuesday, April 12th and tanking on Thursday, April 14th," NASA said.
Engineers discovered a fault with a helium check valve designed to keep the gas from exiting the SLS, thus the test would be changed. NASA will concentrate on fueling the rocket's core stage during the modified test, with "limited propellant operations" on the upper stage.
NASA will be able to move forward with Artemis 1 once the test is completed. The project will send an unmanned Orion spacecraft on a circumnavigation of the Moon to see how the journey will impact human astronauts. The mission will not be scheduled until the wet dress rehearsal is completed. Artemis 1 might launch as early as June if it doesn't suffer any further setbacks this week.