Foolishly I then updated the app on my phone and it then stopped working on mine too!
I have automatic updates turned off in my Google play settings, but it is showing as 'Update Pending' which I will not enable. You turn off auto updates in the play store settings, and bear in mind its 'On' by default. For those of you with Android phones (My phone is a Samsung S22 Ultra, other phones may have subtle differences in appearance) this may help:
Open the Play Store app
Click the icon at the top right
Select settings
Then network preferences
Then Auto Update apps
Then select Dont auto Update apps
Auto updates is a blunt tool, as well as issues such as the railcard app issue it will often try and update over a flaky wi-fi connection which potentially causes problems. I do an update every couple of weeks, obviously excluding any apps where update problems have been reported.
I prefer to manage updates myself.