Dont update to NS firmware 12.00. I someone mentioned in a forum that "the NS Bluetooth-sysmodule was also updated"
symptoms:
If you previously can connect using Joycontrol, you will experience frequent disconnects right after connection and you will need to do a reconnect many times to connect. once its connected it will be fine.
If its the first time connecting to the switch or you did settings ->disconnect controllers". the joycontrol wont connect at all. it will stay in the grip selection screen and not connect