Lets first make sure that the reported status is correct.
I notice that sometimes, the running status of instance in the cluster may not be updated instantly in the console. Do you always see the status as not running even after a while or after refreshing the page ?
You can try using CLI "asadmin list-instances" to see what it says about the status.
if CLI also reports the instance not running, then there is some problem in starting that.
Also, ensure that the node agent is running. Doing 'asadmin list-node-agents' will give you the status of the node agent.
You may also need to look at the node agents or instance log to see what may be the problem.
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