This is annoying. Has anyone else experienced this lately?
Did you move your muse files? Or saved them as a new file with a new name?
No. I had not opened Muse on this particular computer for over a month. Adobe asked me to agree to its terms and conditions before launching the application. I suspect there has been an update or something.
Did you open the Muse file on a different machine? For security reasons the credentials are purged in this case.
No. I have only ever launched the affected files on one machine.
My proposal: Don't think any longer about this, enter you credentials again (I think this will be done in maximum 1 minute), be lucky and see, if it happens again. Every application or computer may have a hiccup. Don't worry about this.