Could run electromagnetics simulation weeks ago, cannot now

As in the screenshot, I have run several electromagnetics simulation runs before, but now it’s disabled for some reason. My account is still listed in the dashboard as academic plan, and my core hours are only at 2 hours out of 2000 allowed. Why could I run the simulations before and not now? I have less than two weeks left to finish my final thesis and I wanted to show some ideal simulation results. I really need to be able to run this sim before the deadline.