It was advised to raise to Microsoft Support as the Office 365 Admin as Support will pull the session ID's and logs to see what is going on with your tenant. If it is the same as the case above then this is likely to be happening across browsers. As Mark mentions in the article, this session expiry should only occur, for example, if you have been in another tab in the browser and have not been in the session awhile.
There is no setting with stream to modify the session timeout currently.
Hope this helps and gives you an answer to your question. If you feel I have answered your question please like the response and set it as the solution. Best of luck with Microsoft Support and I hope they fix the issue soon. I hope to answer more of your questions in the future.