AGM-84H warmup timer stopping after three minutes.

Hello, I am trying to learn how to use the AGM-84H, and I am having an issue with trying to warm up the missile in the F/A-18. Basically, I arm the weapons and switch the plane to A/G mode. On the weapons stores page, I click the weapon button at the top left, and it starts the warm-up timer, counting down from 10 mins; however, for me, when it gets to 7:00 mins the timer goes away and the missile looks like it no longer warming up.

Any ideas on what I might be doing wrong and how to get the missile to warm up and turn on?

Thanks