Tie points data not extracted by PixEx for OLCI L2 WRR

Hello,
I am using Pixel Extraction tool to extract values from some OLCI L2 WRR data. Everything seems to be fine excepted that I do not get any value from tie-point grids.
I tried with an OLCI L2 WFR product and, conversely, it works fine.
There is any step I am missing for WRR data ?
Many thanks