Hi @Tim Martin,
Thank you for the report and info provided! We were able to replicate the issue and added a task on our backlog to fix it on a future release!
In the meantime, if you really need to use the Previous Screen button, as a workaround you can wrap the Tabs Pattern on a platform If with a boolean variable attached (false by default). On the Screen1's OnReady event, you can assign that variable True and it should prevent the issue.
I attached an oml with the workaround.
Best regards,
Bernardo Cardoso