Did you open a case with FMI support? If so what are they saying?
See if you can grab the logs from the FMS logs folder from your old volume. Very interested to see what kind of load you're putting on the box.
What size instance did you have?
There was no load, it was a test server with 8 databases on it, and no one connecting to it other than myself periodically. I had that one running as a t2.medium -- prior to that I was using the c4 series.
I didn't open a case with FMI - I figured they were closed for the weekend.
I'll mount the last snapshot to a new instance after the stack builds again. I'm pretty sure though the logs were on the volumes that get destroyed with the instance. If they wrote the logs out to other amazon cloudwatch it'd be a lot easier.