Description
The rx_outclock port is not available in the ALTLVDS_RX megafunction when using a deserialization factor = 2 in Arria® V devices when regenerating the megafunction from an existing one.
Resolution
You must recreate the ALTLVDS_RX megafunction for the rx_outclock port to be available.
This problem is fixed in version 12.1 of the Quartus® II software.