Multi-temporal Sentinel-1 data registration problem

Hi all,
I have a question:
I processed 30 scenes of Sentinel-1 GRD data in SNAP, and the preprocessing flowchart is as follows:

Because I want to see the changing characteristics of crops in time series images, I want to register the images. So I used the tool: Radar > Coregistration > Stack Tools > Create Stack.

After that, there are still some images with positional deviation:

How do I register the image? Or is there something wrong with my previous processing steps?
Please help me.
Thanks a lot for any help!

are the images from different looking angles (ascending and descending)?

If you have already geocoded the images I recommend using “Product Geolocation” as initial offset method instead of “Orbit”.