Loop is simple enough - Murder Investigation spawns 1/1 token, it gets -1/-1 and dies, that trigger Murder Investigation again.
I waited for around 7 minutes, and there was no loop protection bar at the top of the screen.
Hello @Mangetsu ,
Thank you for all the information provided, this issue will be investigated!
If you have any additional information that you consider relevant, please don’t hesitate to send me 
Rebeca.