ttyACM0 still dropped

I got a Adafruit Circuit Playground and tried to run it on a PC with Debian Stretch 9.6 .

After the first program I uploaded the Circuit's ttyACM0 is not available any more.

The best I got is: It is available for some seconds and I tried this command I found in another topic here:

avrdude -patmega32u4 -cavr109 -P/dev/ttyACM0 -b57600

Connecting to programmer: .
Found programmer: Id = "CATERIN"; type = S
Software Version = 1.0; No Hardware Version given.
Programmer supports auto addr increment.
Programmer supports buffered memory access with buffersize=128 bytes.

Programmer supports the following devices:
Device code: 0x44

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e9587 (probably m32u4)

avrdude: safemode: Fuses OK (E:CB, H:D0, L:FF)

avrdude done. Thank you.

But nothing really helps. The device is not available for the Arduino-software. The Port-Menu is greyed out.

After doing the reset, the red LED blinks for a while and then stops. This is the log from dmesg:

[9488933.127597] usb 3-8: USB disconnect, device number 93
[9488967.949706] usb 3-8: new full-speed USB device number 94 using xhci_hcd
[9488968.091715] usb 3-8: New USB device found, idVendor=239a, idProduct=0011
[9488968.091717] usb 3-8: New USB device strings: Mfr=2, Product=1, SerialNumber=0
[9488968.091718] usb 3-8: Product: Adafruit Circuit
[9488968.091719] usb 3-8: Manufacturer: Adafruit In
[9488968.092589] cdc_acm 3-8:1.0: ttyACM0: USB ACM device
[9488970.288575] usb 3-8: USB disconnect, device number 94
[9489035.957568] usb 3-8: new full-speed USB device number 95 using xhci_hcd
[9489036.099675] usb 3-8: New USB device found, idVendor=239a, idProduct=0011
[9489036.099677] usb 3-8: New USB device strings: Mfr=2, Product=1, SerialNumber=0
[9489036.099678] usb 3-8: Product: Adafruit Circuit
[9489036.099679] usb 3-8: Manufacturer: Adafruit In
[9489036.100478] cdc_acm 3-8:1.0: ttyACM0: USB ACM device
[9489045.787626] usb 3-8: USB disconnect, device number 95

I stopped the modemmanager, tried different USB-ports, but nothing helps.

Do you have any hints for me?

Thanks in advance.

Now I tried on Windows: Same result, just with "COM3" instead of ttyACM0, so I am quite sure it is an issue with the board.

Any ideas how to fix this?