Hi Dewalt
Thanks for posting in the community and I'm sorry to hear that you are having trouble with this. You mentioned that you have been able to get back to edit mode. Could you clarify the steps you are taking before getting stuck in view only mode – e.g. are you trying to use a specific feature or opening/editing a specific file? Could you also send a screenshot of what you see when stuck in view only mode and the version of your browser?
Also if deleting your cookies fixes the issue this means that it was likely caused by browser interference. Would you mind testing if the issue persists when accessing Lucidchart from a different browser? Lucidchart is optimized for Google Chrome so if you haven't already please try opening your account in that browser to see if it resolves the issue.