They Says That on Their Website:
Dear users,
Because of the current market situation, with the latest spike of mining difficulty exceeding 14% (https://bitcoinwisdom.com/bitcoin/difficulty), while the price of Bitcoin continues to decline, the payout was lower than the maintenance fee, which resulted in the balance not increasing and remaining the same. We are considering all possible options, while taking into account the available resources, to optimize the mining process where it is possible.
At the moment, users of HashFlare’s cloud mining services are worried that the company may be preparing to pull an exit scam. This is because the daily payouts are now below the maintenance fee, so users are not making any returns on their investments anymore.
This development comes after the mining difficulty increased by 14% on June 5th. Mining difficulty is increased or decreased relative to the amount of hashing power on the network to keep up with Satoshi Nakamoto’s original design of only releasing a block every 600 seconds (10 minutes). The Bitcoin mining difficulty has not decreased since November 24th, 2017.
For those unfamiliar, cloud mining is a service usually provided in the form of contracts, where users will pay an initial amount for a certain amount of hashing power, for a predetermined amount of time. The purchased hashing power will be performed by machines at the mining companies mining facility and paid out to the customer daily (some cloud mining companies pay out monthly).
A maintenance fee or other fee is usually included when purchasing cloud mining contracts. This allows the contract to be mutually beneficial for both the mining operation and the customer. Cloud mining firms often host their mining equipment in areas with little to no electricity costs to make selling contracts more profitable. However, this maintenance fee now exceeds the payouts for Bitcoin mining contract holders, so all BTC credited to users accounts are instantly removed to pay for the maintenance fee.
Fortunately for investors, HashFlare is being transparent about the situation, expressing that the issue was caused by the rising mining difficulty and declining value of Bitcoin.