I have a 10GB volume attached to my production EC2 instance (It's only 300MB full). In order to do backups, I created a snapshot of it. Then I created a volume from it, which I tried to attach to another EC2 instance. The volume's status shows "attaching" and it never gets attached. I have tried this 4 times, out of which only once it successfully got attached and I could mount it from the EC2 instance. During that one time, it didn't take more than a minute to get attached. All other times it gets stuck in the "attaching" state. I've waited for 3-4 hours, but no help. Only thing I can do then is 'Force detach'. I've been using web UI all this time and not CLI.
What might be going wrong? How can I debug this problem?