Using PTP to control camera never retrieves any data

[Strat00s]

I am trying to use this library to implement a simple PTP (picture transfer protocol) to be able to control my DLSR using Trinket M0.
But no matter what, I never get any data from the camera when using the actual PTP.
I can get all the descriptors just fine, as that's done by the library itself. Using them I set up the device to use correct endpoints and config. But then, no matter what, when I tried to get "GetDeviceInfo" from the camera, both outTransfer and inTransfer return 0, but there are never any data coming from inTransfer.
Here is the function that I call when I press a button connected to pin 1 on my trinket.

void camPoll() {
    int rcode;
    uint16_t length = (sizeof(uint16_t)*2 + sizeof(uint32_t)*2); //dont care about the rest of the container
    uint8_t data[length];
    memset(data, 0, length);
    //little endian
    data[0] = 0x0C;   //len 0
    data[4] = 0x01;   //type 0
    data[6] = 0x01;   //code 1
    data[7] = 0x10;   //code 0

    //send command container
    rcode = UsbH.outTransfer(1, ep_info[BULK_OUT].epAddr, length, data);
    u8x8log.printf("RC: %d\n", rcode);
    uint16_t read = 64;
    uint8_t in_data[64];
    memset(in_data, 0, 64);

    //receive data
    rcode = UsbH.inTransfer(1, ep_info[BULK_IN].epAddr, &read, in_data);
    u8x8log.printf("RC: %d\n", rcode);

    //print data
    for (int i = 0; i < 64; i++) {
        u8x8log.printf("%02x", in_data[i]);
        if ((i + 1) % 8 == 0) u8x8log.printf("\n");
    }
}

And every time, I get return code 0, but no data in "in_data".
Also, after 2 tries, I start to get return code 2 on outTransfer.
I have tried literally everything I could think of (different packet sizes, endians, endpoints), but nothing works.
Does anyone have any idea how to actually use this for PTP?

P.S.: I looked into some PTP libraries (libgphoto2, PTP2.0). I followed them as close as I could, but I never get anything from the camera.