Poloniex and Bittrex withdrawals are out of our hands. We are sorry for the inconvenience. Everyone should contact their support, but if your TX is recorded on a Lisk blockchain you will certainly get the current ARK bonus % that is in effect at that time.
If your Poloniex Lisk is pending or stuck for hours you may want to cancel your withdrawal of Lisk from Poloniex, sell it for Bitcoin, transfer Bitcoin to Bittrex and buy Lisk there and send. Bittrex has had no issues sending Lisk to ARK-TEC so far, but you will probably lose some value in the process. However, it is another option.