We have released version 5.1 for Simple Roster. This update has fixed a bug where rosters are not displayed properly for some users
I keep losing the page when I press any button to try and enter or view any data ! It’s a waste of time having the app ! It’s become useless since you’ve fixed a bug I didn’t have !!
Try deleting the app and re-install again from the app store, you can then restore the backup in “Setting” -> “iCloud Backup”