Zombie walk not responding to GPS / walking

Detailed description of the problem:
I moved to a new phone (Google Pixel XL to Samsung A51). Alarm went off for the first time: sound was different and walking did not reduce the 15m count of movement required to turn off the alarm. I finally uninstalled the app to get it to turn off.

Steps to reproduce:
No idea. Move to a new phone?

Version of Sleep as Android:
20200606 (22058)

Hello Mr Scott,
The Zombie Captcha does not use GPS tracking, but a build-in step counter. Is the step counter working properly on your device?