Error message in popup window when you click the "save" button in "save for web (legacy)":
Adobe Save for Web Error
Could not complete this operation. A write permissions error has occurred.
Tried saving in many different folders, and new folders, inside and outside of dropbox. Restarted everything, updated to latest PS version 22.2.0. Macbook pro Big Sur 11.2.1. The image I'm trying to export is an animated gif.