When attaching either my Smartphone or Tablet, I cannot mount it as a drive
using KDE.

When attaching a new entry shows up, but not mounting is possible (KDE opens a
Dolphin tab with my home drive). I tried my Tablet on an older Computer with
openSUSE Leap 15.1 and it works fine.

Dmesg output Tumbleweed:
[ 9487.630741] usb 1-3.2: new high-speed USB device number 13 using ehci-pci
[ 9487.741295] usb 1-3.2: New USB device found, idVendor=04e8, idProduct=6860,
bcdDevice= 4.00
[ 9487.741312] usb 1-3.2: New USB device strings: Mfr=1, Product=2,
SerialNumber=3
[ 9487.741320] usb 1-3.2: Product: SAMSUNG_Android
[ 9487.741326] usb 1-3.2: Manufacturer: SAMSUNG
[ 9487.741330] usb 1-3.2: SerialNumber: a2a4b0d014967113

Dmesg output Leap 15.1:
[  223.368181] usb 2-1.2: new high-speed USB device number 3 using ehci-pci
[  223.479071] usb 2-1.2: New USB device found, idVendor=04e8, idProduct=6860
[  223.479076] usb 2-1.2: New USB device strings: Mfr=1, Product=2,
SerialNumber=3
[  223.479079] usb 2-1.2: Product: SAMSUNG_Android
[  223.479081] usb 2-1.2: Manufacturer: SAMSUNG
[  223.479082] usb 2-1.2: SerialNumber: a2a4b0d014967113
[  236.204124] usb 2-1.2: reset high-speed USB device number 3 using ehci-pci
[  244.017355] usb 2-1.2: USB disconnect, device number 3
[  244.240095] usb 2-1.2: new high-speed USB device number 4 using ehci-pci
[  244.350526] usb 2-1.2: New USB device found, idVendor=04e8, idProduct=6860
[  244.350533] usb 2-1.2: New USB device strings: Mfr=1, Product=2,
SerialNumber=3
[  244.350536] usb 2-1.2: Product: SAMSUNG_Android
[  244.350539] usb 2-1.2: Manufacturer: SAMSUNG
[  244.350541] usb 2-1.2: SerialNumber: a2a4b0d014967113

Mount with KDE and find two folders:
Card and Tablet

On Tumbleweed I can mount my E-reader and USB-drives at least once (that is
another bug).