Copernicus 30m DEM in Antarctica

I am using Copernicus 30m DEM in my SNAP frameworks for quite some time without problems, now I experience a strange behavior in Antarctica. Here is a simple example when I want to output the DEM from a simple predefined interferogram graph (attached).
TOPSAR Coreg Interferogram_Antartica.xml (5.8 KB)
I have the last version of SNAP and updated, however I am not used to work in polar region so I wonder if it is coming from some precautions/parameters I did not take into account within my graph ?

The two SLCs input images are the following:

The output DEM I display is for IW1.

The phase/coherence looks quite ok at first sight but when zooming we can see some of the patterns (makes sense since I substract topo phase)

Just as an extra info, I obtained same behavior in other part of Antarctica.
I did not figure out yet if it is the DEM that is erroneous or if SNAP does not read properly the DEM.
Thanks a lot for your help !
Best regards

Welcome Tibo, since you are not applying any reprojection I would guess something goes wrong with the handling of the DEM tiles. Do the downloaded tiles look ok?

Hello Marcus,
I do not get any error in the log, looks like SNAP download successfully the tiles, and no apparent errors at the end of the computation (both in the GUI or gpt)
Some of downloaded tiles are indeed empty,
1st tile is Copernicus_DSM_COG_10_S77_00_W051_00_DEM.tif
2nd is Copernicus_DSM_COG_10_S77_00_W059_00_DEM.tif
Could it be related to the recent update of Copernicus data ecosystem ?