Hey Steven,
It sounds to me like a network failure. If the connectivity wasn't strong enough to reach our servers in a timely manner, you could still see a running position on the platform which in reality was already closed as per your input.
Although this issue is rare you can easily solve it by refreshing your browser. In case even a refresh doesn't help, you can always grab a screenshot and send it to our helpdesk.uk@ig.com .
I hope this helps!