We've seen this issue occur when Atlassian Confluence Cloud services went down and stopped responding March 10th to March 14th, 2019.
After that Atlassian seems to have remedied that particular issue. If you see this again please alert us.
We are working on writing automated tests simply to verify whether the Atlassian Cloud Platform is working as intended to catch such issues earlier and mitigate them. It's a full time job