Gpt hangs on execution via python but runs fine via snap interface

hi all
im back to try running the interferometry process on s1 using python to run each step by rebuilding the graphs and running then via gpt.
see this link for more details

so far i tried running the same graph in snap (read-dtc-write using SRTM 1Sec HGT and it completes in 7 min). running the same graph via gpt - and the computer seems to complete the task, builds a file but hangs and doesnt complete and i have to break it. all other steps work fine.
right now i am running the same graph in python only the dem is external (i provided a 4m dem). and hope it will work.

any ideas why this is happening? anyone experienced the same?


i am looking for a good overview on the interferogram procedure with sar s1. i looked around built tis lovely code and run it to the best of my knowledge but i have a bunch of products. which one is the band that contains the delta in heights?
Unw_Phase_ifg__VH ( is where the date of the two images appears - in this case 20190705-20200711)
or is it
displacement_slv3_&_VH (& is where the date of the two images appears - in this case 20190705)

anyway if anyone here can direct me to successful implementation examples or wants to have a chat - id be delighted.