HTCC-AB01 sub 125kHz bandwidth

As the AB01 dev-board uses SX1262 chip it should in theory be possible to set the bandwidth as low as 7.8kHz.
In the example code is see those settings listed as reserved
#define LORA_BANDWIDTH 0 // [0: 125 kHz,
// 1: 250 kHz,
// 2: 500 kHz,
// 3: Reserved]

However the library does seem to have the required modulation parameters
const RadioLoRaBandwidths_t Bandwidths[] = { LORA_BW_125, LORA_BW_250, LORA_BW_500, LORA_BW_062,LORA_BW_041, LORA_BW_031, LORA_BW_020, LORA_BW_015, LORA_BW_010, LORA_BW_007 };

When trying settings sub 125kHz however my P2P communication breaks. Anyone tried using the HTCC-AB01 with a bandwidth below 125kHz?