Back geocoding producing empty stripes in slave product

In one and only one of the 3 sub-swaths, i.e. sub-swath 1, the image S1B_IW_SLC__1SDV_20191017T205036_20191017T205104_018520_022E57_724A (used as either master or slave) leads to a slave product that contains empty stripes.

I tested back geocoding it in combination with

Does this happen every time you run Back Geocoding on this sub-swath?
You could slightly change some of the parameters.
Do all sub-swaths look alright before this step?

Back geocoding works perfectly well in SNAP when using these 2 inputs:
which have a longer temporal baseline

I am using these parameters

The sub-swaths looks ok before back-geocoding: is there a way to check for specific issues?

Sorry I was confused earlier. Both 6- and 12-day pairs can be from the same track. Have you opened the bands of the problematic product to see if they are filled with data normally?

please give it another try with SRTM 1Sec

I tried with SRTM 1sec and the stripes are still there in the slave product

Does the secondary image have full bands in it? Or is the data missing already in the beginning.

The inputs seem to be both ok