Please tell me the course of this things
I'm in contact with them and they have yet to confirm the 5.0.1 upgrade, so it could be simply that being performed. I sent them a request for a status update.
It is still disabled, yet on CMC there is trading reported on Poloniex during last few days. Any idea what is going on?
Trading is online at Poloniex. Only deposits and withdrawals are disabled. I sent them a tweet further requesting an update. I expect they'll get back to us on Tuesday at the latest. Today (Sunday) and Monday are holidays, but I don't know how Poloniex deals with those.
In the meantime you may trade NuShares at Cryptopia on the newly initiated NSR/BTC pair.
Looks like maybe NSR is being officially delisted. See https://www.reddit.com/r/BitcoinMarkets/comments/66908w/poloniex_announces_the_pending_delistment_of_17