Hi Peter,
The best thing to do would be to recreate the issue again, note the time of failure, then check the web-critical.log to see what is happening (downloaded from the SZ web interface:
Application Logs & Status > select control plane from drop-down > Expand 'Web' > click web-critical.log.
The Support team can help further with log analysis, if you share the log(s) in your existing case.
On another note, looking at the image you shared, it looks like you are saving a cluster backup every day. Was that purely whilst you are testing, or is it your intention to save a clster backup every day and store offline? A regular cluster backup is definitely a good thing, but every day is a bit unnecessary in most cases.
Regards
James