topsStack run_01 hangs at "Processing line: 1" during Topozero

[GauravDev20]

Problem

I am processing Sentinel-1A TOPS data using ISCE2 topsStack with the
interferogram workflow.

The processing gets stuck during run_01_unpack_topo_reference,
specifically during the Topozero/topo step.

The process remains at:

Processing line: 1 / 7596

for several days without progressing.

I interrupted the process with Ctrl+C and obtained a traceback showing:

topo (isce/components/zerodop/topozero/Topozero.py:125)
call_topo (topo.py:71)
<listcomp> (topo.py:109)
main (topo.py:109)

The process was therefore spending its time inside Topozero.

Configuration

ISCE2 was installed in a Conda environment.

Python:
3.11.6

Workflow:
topsStack
interferogram

Sensor:
Sentinel-1A IW SLC

Swaths:
IW1 IW2 IW3

Reference date:
2020-02-10

Number of Sentinel-1 acquisitions:
7

AOI:
South = 28.17
North = 28.53
West = 76.23
East = 77.33

DEM:
output_hh_new.tif

The DEM is GeoTIFF, EPSG:4326.

The machine has approximately:
RAM = 15 GB
available RAM during testing = ~11 GB
Swap = 46 GB
Disk available = ~481 GB
Filesystem = ext4

The topo configuration currently contains:

numProcess : 1

Observations

Reference extraction successfully found:

IW1: 4 bursts after cropping
IW2: 4 bursts after cropping
IW3: 0 bursts after cropping

The IW3 zero-burst condition appears to be because the AOI does not
intersect IW3.

The DEM itself appears valid. GDAL statistics previously showed:

Minimum = 180
Maximum = ~471.7
Valid percentage = 100%

The precise orbit for the reference acquisition is available:

S1A_OPER_AUX_POEORB_OPOD_20210317T071120_V20200209T225942_20200211T005942.EOF

I also confirmed that disk space and swap are not exhausted.

Question

What could cause Topozero to remain at:

Processing line: 1 / 7596

for several days without producing the geometry files?

Is there a recommended way to diagnose or run Topozero for individual
bursts/IWs, or a known issue with this version of ISCE2/Python 3.11?

I would appreciate guidance on whether this is a Topozero problem,
a multiprocessing issue, an input geometry issue, or an installation/
version compatibility issue.

I can provide the complete topo.py traceback, configuration file,
system information, and run log if required.