I will start some Nicehash mining later on my rig and see if I can reproduce it.
Usually it should not disconnect - at least there is nothing forcing it to do so. Switching epochs (for Nicehash or Zilliqa dual mining) works without reconnect (unless pool decides to close connection (e.g. ezil does so while shardpool does not).
Which NH server you are on? Will give the same a run
I'm Use Eu server. Not so often but sometimes this disconnections and reconnections to stratum server is happens for me. Other miners works without disconnections. So this is some problem in lol miner.
Miner quick reconnects in 1 sec and again subscribes to extranounce and authorises. It take some time though.