Every now and then (perhaps once per week/month, depending on usage) the app loses the login state - after opening it offers to login or register. In most cases force-closing the app and opening it fixes this.
Sometimes (has happened 3 or 4 times to me) this does not help, and I have to log in again (which is an issue on the field as I have my credentials safely in the laptop…).
On top of this, all local settings are lost in these cases (3G/4G upload, capture settings etc).