I've asked a question about DP1.4 rxss iic-over-aux on 11/03, it's about rxss DDC/CI couldn't work functionally with source connected to dock station (DELL WD19TB). (But it works normally when connects to monitor)
As @florentw suggested to update fw, I've updated the dock station fw to the latest version, but nothing changed.
Furthermore, I found the same problem occurs when using HP dock station USB-C Dock G5.
Attach logs for your reference :
111_AUXraw.txt & 112_AUXraw.txt : with DELL dock WD19TB => DDC/CI fail
116_AUXraw.txt : without DELL dock WD19TB => DDC/CI OK