Hi @PJ3771, welcome to our forum and I'm sorry to hear about this.
There is no setting in the phone that will turn off the charging when the phone is powered on, so we will need to troubleshoot a bit here to see what the cause of this behaviour is.
Is this something that you have started to experience very recently, for example after updating your phone or after installing a new application? Have you also tried charging the phone directly from a USB port instead of using the wall mounted charger or the other way around?
As @uliwooly recommended, if one of your friends, colleagues or family members also have an Xperia device, you can ask them nicely if you can borrow their charger and/or cable and try charging your phone when it is powered on.
Just so we can make sure that a downloaded application isn't the cause of this, could you please try and restart your phone in safe mode and try charging it in this mode when it is powered on and see if there has been any change.
Let us know how it goes!
