Hi, I had this same issue, but in my case it's strange because I have the S9 which I no longer get updates I believe.
So unfortunately after doing the mistake of deleting the app it was when I found out how I could have solved the issue.
I got confused bc I had 2 Samsung accounts with different emails, one being my Google email. When I was trying to sign in I should have signed with my Google email instead of the other one.
I signed off my Samsung account. Then when you go to the secure folder it gives you the option to uninstall. But you must sign in with the Samsung account( email) associated to the secure folder so then it will automatically give you the option to change your password.
As I said I deleted the secure folder, When I set it up again with my Google email it looks like all the data was wiped out, I cannot even restore it.
If its the same account why all the data disappeared, and also why Iam not able to restore it.
I have been using it for so many years, yet the safest place is in a USB drive, at least in there it's in ourcontrol.