The behavior shield as was is integrated into the file system shield. avastUI > Settings > Antivirus - scroll down to the Exclusions. The File Paths would apply to the file sustem shield and the DeepScreen and Hardened mode tabs speak for themselves.

Can you attach a screen shot of the alert window as I suspect that this may be the new functionality in the file system shield (not necessarily behavior element), possibly the hardened mode or deep screen.