App opens but flags 'Invalid credentials'

Hi,
I have the App on my iPhone, recently updated for software and the App.
I open it and it immediately gives me that message. No problem logging in here, and I didn't change my settings.
What to do?
Thanks,
Alan

@Tom-Crean

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@Tom-Crean

I'm unable to reproduce this.

iPhone type (and iOS version too), if possible?