DisplayPort Sink (Quartus 18.1) – horizontal pixel offset.

We are experiencing an issue with the DisplayPort Sink IP core (Quartus Prime 18.1), where the captured video stream becomes horizontally shifted after some runtime. The system works correctly after reset, but after a variable period (typically several minutes), the image suddenly shifts horizontally by a constant number of pixels (hundreds of pixels). The image remains stable but shifted. After longer time (tens of minutes), the image may spontaneously recover, and the cycle repeats. This behavior only appears when the input signal is routed through a DisplayPort optical extender (G&D). Without the extender, the system operates correctly and indefinitely stable.

This system design is constrained to Quartus 18.1 (cannot migrate easily) - We are primarily looking for a workaround or confirmation of known limitation - Not asking for redesign or migration unless necessary