There is a known issue with the FireStudio Lightpipe clocking externally over ADAT or BNC at 48 kHz and 96 kHz. However, the FireStudio Lightpipe will externally lock at 44.1 kHz or 88.2 kHz.
When using the FireStudio Lightpipe as the master clock, you can clock all digital devices via ADAT or BNC at 44.1 kHz, 48 kHz, 88.2 kHz, or 96 kHz without issues.
If you are having difficulty clocking externally at 44.1 kHz or 88.2 kHz, verify that both the FireStudio Lightpipe and your external word clock generator are set to the same sample rate and you have the correct digital input on the FireStudio Lightpipe selected as the clock source.
Please note: the FireStudio Lightpipe employs JetPLL technology and has an extremely reliable internal clock with less than 20 ps of jitter and has been compared to high end stand alone clock generators like the Digidesign Sync I/O and Apogee Big Ben in performance shoot outs. Because of this, using it as the master clock for your studio will provide you with both a stable word clock generator and high quality digital sync resulting in a better overall sound.
At this time, there is no plan to resolve this issue. PreSonus apologizes for any inconvenience.