We received a very helpful replay from the Espressif RF Support group.

Basically, for the ESP32-C3 you should burnt the bootloader.bin @ 0x0 not 0x1000 as shown in the documentation

Problem solved!

Thanks very much!

We're an OEM and we're trying to perform BLE DTM testing on the :
ESP32-C3-MINI-1U-N4

Note that we've attached screenshots in an attached PDF file.

We're using:
EspRFTestTool_v3.6_Manual

We're trying to load these files:

\\sharebear\sq\sqwork\technical\reference\Datasheets\Espressif\RF-Test ...