Game parameter gets below its min value

Question

Hello,

I have a Game Parameter with a range from 0-100. Initially it is set to 0. When I call an event from Unity which reduces the value by 15, it is set to -15 instead of staying at 0, as I would expect.
I am monitoring the value with Unity.

How can I fix this behaviour?

I am using Wwise 2019.2.9.7459 and Unity 2019.4.21f1.

Thank you for your help!