I upgraded nrfjprog today to support the nrf5340-dk, and nrfjprog stopped exiting.
I narrowed it down to 10.12.2 working and 10.13.0 hanging.
$ nrfjprog --reset
Applying system reset.
Run.
On 10.12.2 it exits, on 10.13.0 it never exits, but both provide the same output.
I've attached logs from both.
I'm running debian bullsyeye 11, and I've been installing nRF commandline tools debs from their download page: https://www.nordicsemi.com/Products/Development-tools/nRF-Command-Line-Tools/Download?lang=en#infotabs