The Intel® Stratix® 10 device E-Tile Transceiver Toolkit “RX CDR is locked to data” virtual LED does not live update by default. The initial state of the CDR lock signal is used for the LED. This may be initially toggling.
To work around this problem and see the current state of the CDR “RX CDR is locked to data” LED you can tick the “live updating” tick box in the RX channel toolkit.
This problem may be fixed in a future version of the Intel Quartus® Prime Transceiver Toolkit.