I'm a long time user of the server based Confluence, but new to Confluence Cloud.
After I created my first page, I was not presented with the option to edit it. No pencil icon, no reaction to a keypress of "e".
After reloading the page, that was fixed, the pencil was there and I could go into edit mode, change some text and save the page.
When I tried to edit again, I could enter the edit mode, but this time, there was no cursor, so no chance to change text. Clicking on active elements like images, in order to get to a "context menu" did also not work.
After reloading a couple of times, that worked again, also.
Google gave me several similar problems, which were from about 11/2019, with many different answers. I did the websocket check that some answers suggested (https://websocketstest.com/) , but everything seems fine. My browser is Chrome Version is the latest (83.0.4103.106).