Turned off a dedicated host AWS mac m1 and now can't start it again

I started a m2.metal EC2 instance, dettatched the root volume, attached it back, rebooted and now I get this error: "Dedicated host h-0c86b2bf6ea52b192 has insufficient capacity to launch the instances in this request."

What on earth is this? It's a dedicated host - where is the insufficient capacity coming from? And I'm paying a 24h minimum for this mac instance.