There appears to be a fork at the moment. The result of that is that many transactions can be orphaned. Probably best to wait with further transactions till both forks have merged again. It is unclear when that may happen. We have notified others who will be looking into it. It may resolve itself after a while. Will keep you updated in this thread.
At time of writing the highest block number is 1,540,003 https://nu.crypto-daio.co.uk/#
The other fork is about 30 blocks behind. https://nuexplorer.ddns.net/ and https://svr1.nubitsexplorer.nu/chain/Nubits
Just noticed that Bittrex also reports issues with their blocks and transactions are not likely to come through.