Ignore the fiat amounts... given that BTC was worth about 50% more back in December, looking at fiat amounts is confusing. What were the
BTC amounts mined and transferred?
It's possible that nicehash have deducted a withdrawal fee... And given the difference between BTC/USD rate then and now it's possible the amount of BTC received for mining was quite small and any fixed fees ate a big chunk. It also looks like they take a service fee if your payout is less than 0.1 BTC:
Payouts for balances less than 0.1 to external wallet 5%
Have you checked your Nicehash dashboard on the Nicehash website to see the details of the calculations/payments and any fees involved?