Damage meter messing up when party changes

I noticed that when someone leaves a party (or we kick him because he takes forever to come inside), then the one taking his place doesn't show on damage meter.

Sometimes it even affects other members.

Well yes, I stopped fighting its automatic startup at some point, and kept it.

I know it may be less accurate than Shinra, and has less details, but meh...

This way I truly don't have any third party and I'm good with this.