Hello @Neil
Welcome to the LastPass Community.
About your issue, I'm very sorry for any inconvenience this may have caused you. I have completed some updates from my side, such as clearing the corrupted sessions and updating your account. I need you to follow these steps to complete the basic troubleshooting on your mobile:
HildaC
I have deleted the app, restarted the device and reinstalled. It made no difference. Your answer then referenced Android but I clearly stated the issue is on my IOS devices.