I have had this issue since last fall. I have an iPhone 10, I believe. I upgraded to premium and can’t use it because it will not sync my files. I don’t see any responses to this issue but several posts on here with same issues but no solutions. I have forced close, restarted phone, deleted and reinstalled app (losing files.) They told me to leave the app open at nighttime to let it sync overnight. Nothing happens still. I put in another support ticket.