Looks like your network is not behaving like you’d expect ! The kpi indicates that something is wrong. Doing a rollback brought you back the pre-trial performances?
I don’t know what is the status of this feature today, but in the past some phones were having issues.
Could you do a drivetest and check :
1/ fast reselection info are correct
2/ the phone connects to the right 3G LAC at the end of the call.