iPhone 11 won’t open window to sign in when you click sign in

I have scoured the internet and have been unable to find a solution. My Branches YW president is unable to login to the Tools app. When you open the app it opens and has a button to click sign in, but when you click sign in it opens a window with nothing on it. I am trying to help her get it fixed and have tried deleting the app and reinstalling it, restarting the phone, and deleting all of the data associated with the app and nothing has worked. Any help would be greatly appreciated!

Member Tools requires iOS16 or later. What version is being used on this phone?

It has iOS18.

The sign-in page in Member Tools is a web page that loads in the app. Does she have a default browser other than Safari set in iOS Settings? If so, it might be worth trying setting the default browser to Safari to see if the sign-in page starts working.
If that works, I'd recommend sending feedback through Member Tools to report the bug.

(I know this reply is a couple of months after the initial report, so hopefully things are working by now, but just in case… )