Before I continue, here are the last 3 log files generated:
https://devforum.roblox.com/t/authentication-issue-in-studio/642417
Title pretty much says it all.
When developing, I use 2-player client test, so I can try to strain both the server and client separately to find issues quicker. When I finished some code, I clicked the “Start” button for running the windows needed.
Afterwards, a single Studio window opened requiring me to log in, with an orange error message saying “Authentication failed.” This reproduced multiple times in that session, so I thought I would restart studio.
Before I restarted, I did a publish, publish as, and a save as local copy. Re-opening Studio still prompted me with the orange error text below the login screen, so I proceeded to log back in. When I opened my project (publish bed version), no progress saved despite Roblox multiple publishes. Thankfully though, my local copy saved just fine and I was able to recover completely.
Hope I provided enough information, but feel free to shoot me some questions if needed 