The congested network is the cause of this issue. The ETH network is currently 100% full and that is why transactions are taking longer than usual to get confirmed. It is required to have atleast 50000 gas limit for the transaction to be confirmed in a couple of hours. Lower gas limits will eventually take a longer time to be confirmed.
Ethereum now is facing troubles with the system and heavy loads that cause in slowing transactions to confirmed. But there is another option is by changing gas limit into higher and it will gives you chances for a faster confirmation. This is what I've did awhile ago..