Why does fingerprint sensor not work when phone is charging? I often face this issue. The fingeprint sensor does not work and sometimes the touch also misbehaves when phone is charging.

Why does this happen  and how to fix this?

I experienced this  issue with Mi Note 4, as well as Redmi 4A.
As requested by OP posting answer, in response to my comment (now deleted) based on my experience 


  Having a clean power supply, using original charger + USB cable, setting up finger prints again are the common things that work...


I am not  sure as to why touch sensor  works only with original charger but posting as it may help, as it helped OP