CosmoSkyMed SLC Spotlight products coregistration spatial shift

Hi, I would like to coregister two CosmoSkyMed SLC Spotlight products, but I am having some problems with SNAP.
I calibrated the products and then tried to coregister them.
After the coregistration, the slave image appear spatially shifted, so the result it is unusable.
The products are from the same sensor, same track, same geometry, left look and same acquisition mode.
The same procedure is successful if applied to CosmoSkyMed Stripmap products.
Is there a problem on how SNAP handles CosmoSkyMed products or I am doing something wrong?

You can try to enable coarse registration and increase the number of GCPs.

I used 10 000 GCPs but the problem is still present

I also tried to enable coarse registration but the problem persists

hmm, you can give DEM-based coregistration a chance.

DEM-assisted coregistration is successful, but I wanted to avoid it.

If I try to coregister two CosmoSkyMed Left Looking products, SNAP simply shows “-1”.
The coregistration is successful if I use Right Looking products.
Is there any known problem with SNAP and Left Looking problems?

did you apply any pre-processing before the co-registration?

I calibrated the products, as requested inside the SNAP documentation.
I also tried without the calibration: the result is the same.

Maybe the products were not downloaded/extracted correctly? Did you test to open them as single images first?

I tested two CSK right looking images and did not have any error

Did you select “Orbit” as offset method?

I forgot to mention that this problem only occur if I select “save as complex output” during the calibration.

I tested to open the products as single images first and selected “Orbit” as offset method, but the problem persists.

you said above that the problem occurs with both calibrated and raw products - what’s the case here? Does it work with raw products or not?