Smarty App won't log in (S22 Ultra)

Both myself and my wife have Smarty accounts and the latest Smarty App.

I have a Samsung S25Ultra and my wife has the S22Ultra which up until now both have been able to log in to the app.

Mine works fine and can log in on the web and my Smarty app.

My wife's does not allow her to log in on her mobile app but does so on the web.

I have checked her mobile for latest software both on the app and her Android software. All current.

She contacted Smarty about the app issue, and we have tried their suggestions to clear the cache from her app and uninstall and re-install the app again, but this does not cure the problem. She has also tried changing her password (access through her web account), but the app still won't log in. Just get a circular arrow going round and round.

Interestingly I tried logging in to her Smarty account on my own Smarty app on the S25Ultra, and it logged in.

So it appears to be a problem with the S22Ultra, but aside from uninstalling the app and updating the phone's software, nothing seems to help to enable her to log in where she previously used to.

As it happens, my Mother has the same issue with her S24Ultra. Same dilemma.

Has anyone experienced the same with these 2 particular Samsung models recently, or have a suggestion to try to resolve this please?

Any help appreciated thanks. :)