In (PG066), the JESD204 v5.2 LogiCORE IP Product Guide, Figure 3-8 describes Deterministic Latency across the JESD204B Link.
Figure 3-8 shows SYNC~ going high before the transmit device starts transmitting, while the text describing this states "SYNC~ signal going Low".
Which is correct?
SYNC~ is an active low synchronization request signal, therefore it is deasserted by going high.
The text describing SYNC~ behavior on page 54 of (PG066) v5.2 should state:
"When the transmit device detects the SYNC~ signal going High, it waits until the next LMFC crossing and starts transmitting data."
(PG066) v6.0 includes this updated accurate description.