Thunderbolt device does not detect when connected to the system while running in DC mode with a low battery charge

You may encounter a situation where your external Thunderbolt 3 device (e.g. external thunderbolt HDD) is not recognized when connected to the system, while the system is running in DC mode (battery power) and the battery charge drops below 20%. If the Thunderbolt 3 device was attached before the battery charge runs low, it will remain accessible even after the battery capacity is low.

The system is working as designed.

By default, Windows 10 automatically enables battery saver mode when the battery charge runs low and causes the Thunderbolt 3 device not to detect.

Power the system with AC adapter when this issue occurs.