How to find all connected removable USB storage devices in Windows?

I'm writing a program that processes USB drives, to get information about connecting a new device, I signed up for a window message WM_DEVICECHANGE. But I, of course, do not receive messages about the devices that were connected before my program was launched. To process such devices, I wrote a search function, but I get a strange result. It finds my flash drive, but does not recognize it to be removable. Why? Function

bool FindConnectedRemovableUsbstorDevices(std::list<std::wstring>& UsbList)
{
    std::wstring ClassGuidString(L"{53F56307-B6BF-11D0-94F2-00A0C91EFB8B}");
    GUID ClassGuid;
    BYTE buf[1024];
    PSP_DEVICE_INTERFACE_DETAIL_DATA_W pspdidd =         reinterpret_cast<PSP_DEVICE_INTERFACE_DETAIL_DATA_W>(buf);
    SP_DEVICE_INTERFACE_DATA spdid;
    SP_DEVINFO_DATA spdd;
    DWORD size;
    SP_DEVINFO_DATA dev_data;
    DWORD properties;


    if(NOERROR != CLSIDFromString(ClassGuidString.c_str(), &ClassGuid))
        return false;

    HDEVINFO dev_info = INVALID_HANDLE_VALUE;
    dev_info = SetupDiGetClassDevs(&ClassGuid, NULL, NULL, DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);

    if (dev_info == INVALID_HANDLE_VALUE)
        return false;

    DWORD index = 0;
    BOOL ret = FALSE;

    spdid.cbSize = sizeof(spdid);

    while (true)
    {
        ret = SetupDiEnumDeviceInterfaces(dev_info, NULL, &ClassGuid, index, &spdid);
    if (!ret)
        break;

    size = 0;
    SetupDiGetDeviceInterfaceDetail(dev_info, &spdid, NULL, 0, &size, NULL);
    //Get required size

    if (size == 0 || size >= sizeof(buf))
        continue;
    //prepare structs
    ZeroMemory(reinterpret_cast<PVOID>(pspdidd), 1024);
    pspdidd->cbSize = sizeof(*pspdidd); // 5 Bytes!

    ZeroMemory(reinterpret_cast<PVOID>(&spdd), sizeof(spdd));
    spdd.cbSize = sizeof(spdd);

    BOOL res = SetupDiGetDeviceInterfaceDetail(dev_info, &spdid, pspdidd, size, &size, &spdd);
    //Get info
    if (!res)
        continue;

    HANDLE drive = CreateFileW(pspdidd->DevicePath, FILE_READ_ATTRIBUTES,
        FILE_SHARE_READ | FILE_SHARE_WRITE,
        NULL, OPEN_EXISTING, 0, NULL);//open device
    if (drive == INVALID_HANDLE_VALUE)
        continue;

    printf("\n%S\r\n", pspdidd->DevicePath);

    DWORD bytes_returned = 0;
    BOOL b = DeviceIoControl(drive, IOCTL_STORAGE_CHECK_VERIFY2, NULL, 0, NULL, 0, &bytes_returned, NULL);
    if (!b) //check is card reader?
    {
        printf("IOCTL_STORAGE_CHECK_VERIFY2 error = %d\r\n", GetLastError());
        goto stop_process_device;
    }

    bytes_returned = 0;
    STORAGE_DEVICE_NUMBER sdn;
    //Get Drive number
    b = DeviceIoControl(drive, IOCTL_STORAGE_GET_DEVICE_NUMBER, NULL, 0, &sdn, sizeof(sdn), &bytes_returned, NULL);
    if (!b)
        goto stop_process_device;
    RtlZeroMemory(&dev_data, sizeof(SP_DEVINFO_DATA));
    dev_data.cbSize = sizeof(dev_data);
    if (SetupDiEnumDeviceInfo(dev_info, sdn.DeviceNumber, &dev_data))
    {
        //check property
        b = SetupDiGetDeviceRegistryProperty(dev_info, &dev_data, SPDRP_REMOVAL_POLICY, NULL, 
            reinterpret_cast<PBYTE>(&properties), sizeof(properties), NULL);
        if (b && properties != CM_REMOVAL_POLICY_EXPECT_NO_REMOVAL)
        {
            UsbList.push_back(pspdidd->DevicePath);
            printf("REMOVAL\r\n");
        }
    }
stop_process_device:
        CloseHandle(drive);
        index++;
    }
    SetupDiDestroyDeviceInfoList(dev_info);
    return true;
}

And output

\\?\usbstor#disk&ven_generic-&prod_ms#ms-pro#hg&rev_1.00#20090703819900000&1#{53f56307-b6bf-11d0-94f2-00a0c91efb8b} 
IOCTL_STORAGE_CHECK_VERIFY2 error = 21 
\\?\ide#diskst3500418as_____________________________cc38____#5&5c6cfd6&0&1.0.0#{53f56307-b6bf-11d0-94f2-00a0c91efb8b} 
REMOVAL 
\\?\usbstor#disk&ven_generic-&prod_sd#mmc&rev_1.00#20090703819900000&0#{53f56307-b6bf-11d0-94f2-00a0c91efb8b} 
IOCTL_STORAGE_CHECK_VERIFY2 error = 21 
\\?\scsi#disk&ven_ocz&prod_revodrive3_x2#5&19ad1f72&0&000000#{53f56307-b6bf-11d0-94f2-00a0c91efb8b} 
\\?\ide#diskst1000lm014-1ej164______________________sm30____#5&2ea7e938&0&0.1.0#{53f56307-b6bf-11d0-94f2-00a0c91efb8b} 
\\?\usbstor#disk&ven_sandisk&prod_extreme&rev_0001#aa010823150434152862&0#{53f56307-b6bf-11d0-94f2-00a0c91efb8b} 
\\?\ide#diskwdc_wd1002fbys-02a6b0___________________03.00c06#5&2ea7e938&0&0.0.0#{53f56307-b6bf-11d0-94f2-00a0c91efb8b} 
REMOVAL

Error 21 is empty card reader. Sandisk is my flash. In Debug i saw that SetupDiGetDeviceRegistryProperty return property CM_REMOVAL_POLICY_EXPECT_NO_REMOVAL, but i really don't know why...

I don't know why my fisrt method of detection removable media works so strange, but method of RbMm works great. I send IOCTL query to every found device with IOCTL_STORAGE_QUERY_PROPERTY with StorageDeviceProperty and look for STORAGE_DEVICE_DESCRIPTOR.RemovableMedia field. All my devices recognized successfully and right.