Did you flashed the module on your custom PCB correctly? Are you sure you are not in Bootloader mode instead of normal flash mode? Have you looked at the output of the LOG UART? Is the module logging anything at all in the LOG interface?

Related Information:
ESP-AT FW v4.0.0 release
ESP32-C6-Mini-1U (ESP32-C6 DevKitM-1)

AT Commands sequence used:


ATE0
AT+BLEINIT=2
AT+BLEADVPARAM=50,50,0,0,7,0,,
AT+BLEADVDATA="020106030302A00A09736D6172745F6D6174"
AT+BLESPPCFG=1,1,7,1,5
AT+BLESECPARAM=13,0,16,3,3,1
AT+BLESETKEY=654321
AT ...