Re-Init of SDIO Interface does not work

[Simsys]

I would like to use SD cards in my project, which can also be changed during operation. To do this, it is necessary to reinitialize the SDIO peripherals. Unfortunately, this does not work. Based on the example sd.rs the following code:

#![no_main]
#![no_std]

use panic_rtt_target as _;
use rtt_target::{rprintln, rtt_init_print};

use cortex_m_rt::entry;
use stm32f4xx_hal::{
    pac,
    sdio::{ClockFreq, SdCard, Sdio},
    prelude::*,
};


#[entry]
fn main() -> ! {
    let device = pac::Peripherals::take().unwrap();
    let core = cortex_m::Peripherals::take().unwrap();

    let rcc = device.RCC.constrain();
    let clocks = rcc
        .cfgr
        .use_hse(12.MHz())
        .require_pll48clk()
        .sysclk(168.MHz())
        .hclk(168.MHz())
        .pclk1(42.MHz())
        .pclk2(84.MHz())
        .freeze();

    rtt_init_print!();

    let mut delay = core.SYST.delay(&clocks);

    let gpioc = device.GPIOC.split();
    let gpiod = device.GPIOD.split();

    let d0 = gpioc.pc8.internal_pull_up(true);
    let d1 = gpioc.pc9.internal_pull_up(true);
    let d2 = gpioc.pc10.internal_pull_up(true);
    let d3 = gpioc.pc11.internal_pull_up(true);
    let clk = gpioc.pc12;
    let cmd = gpiod.pd2.internal_pull_up(true);
    let mut sdio: Sdio<SdCard> = Sdio::new(device.SDIO, (clk, cmd, d0, d1, d2, d3), &clocks);

    loop {
        match sdio.init(ClockFreq::F24Mhz) {
            Ok(_) => {
                let nblocks = sdio.card().map(|c| c.block_count()).unwrap_or(0);
                rprintln!("Card detected, nbr of blocks: {:?}", nblocks);
            },
                Err(_err) => rprintln!("Init Error"),
        }
        delay.delay_ms(3000u32);
    }
}

The output is as follows. Replacing the SD card does not change anything.

Card detected: nbr of blocks: 1955840
Init Error
Init Error
Init Error
...