Saved views are saved locally in your browser which basically means if you do any of the following they will disappear and go missing:
clear your cache or cookies
Trust me, we know this isn't ideal so the team are working on changing this so you can access from anywhere, BUT as a workaround you can actually save your Saved Views as bookmarks. That way they won't disappear when you clean house!
Note: Speaking of browsers, did you know that Style Arcade is optimised from Chrome? So if you're finding things might be a little off it might be because you're using Safari or Internet Explorer.