Hi,
Your server might be overloaded. I’ve tried to open the back-end panel, but it took around 3 minutes to open.
Then I have tried multiple times to make a new index, but sometimes it failed immediately, sometimes it went for a longer time. This indicates a server overload to me, as it should have failed each time at the same point, but it did not. I usually recommend a server restart in these cases, but if the traffic is too great, it might not resolve the issue.