Why are my sound profiles changing when charging?

[AC Question]

Sound profile changes when charging

Hi,

This may sound like a daft question, but why does my Samsung A5 change sound profile when it's plugged in?

I have the do not disturb setting enabled which for night time use is great, but then when I plug the phone in it changes profile and I get notification sounds etc. The only way to stop this is to change the profile back to silent, which kinda defeats the point of the automatic do not disturb...

I've looked through the settings, but can't find a way to disable this (unless I'm being blind...)

Thanks