Time out error when writing to 128k Flash memory on hardware

[GearsProgress]

Initializing the Flash size as 128KB and then writing data causes a time out error. This issue only happens on physical hardware, not emulation. Running the following program on mGBA with a Flash 128KB save prints "all good". However, when uploaded to a GBA through Multiboot with a copy of Pokemon FireRed inserted, it returns "Two: 5", which refers to a time out error. The only other thing included besides the libsavgba library is Tonc's Text Engine for output.

int main(void){
	REG_DISPCNT = DCNT_MODE0 | DCNT_BG0 | DCNT_BG1 | DCNT_BG2 | DCNT_BG3 | DCNT_OBJ | DCNT_OBJ_1D;
        tte_init_se(3, BG_CBB(3) | BG_SBB(28) | BG_PRIO(0), 0, CLR_WHITE, 14, NULL, NULL);
	flash_init(FLASH_SIZE_128KB);

	u8 test = 1;
	int one = flash_read(0x1D7F0, &test, 1);
	if (one != 0){
		tte_set_pos(0,0);
		tte_write("one: ");
		tte_write(std::to_string(one).c_str());
		while(true){}
	}
	int two = flash_write(0x5000, &test, 1);
	if (two != 0){
		tte_set_pos(0,0);
		tte_write("two: ");
		tte_write(std::to_string(two).c_str());
		while(true){}
	}
	int three = flash_write(0x10000, &test, 1);
	if (three != 0){
		tte_set_pos(0,0);
		tte_write("three: ");
		tte_write(std::to_string(three).c_str());
		while(true){}
	}
	tte_set_pos(0,0);
	tte_write("All good!");
	while(true){}
}

Thank you for your time!