Bus 001 Device 005: ID 0cf2:6250 ENE Technology, Inc. SD card reader (UB6250)
This card reader uses the ums-eneub6250 module and needs firmware to operate correctly which is currently not included in the Debian firmware-linux or firmware-linux-nonfree packages.
The way I have gotten around the problem at the moment is to downloaded the Ubuntu linux-firmware package and extracted the deb package to copy the directory ene-ub6250 from the extracted directory /lib/firmware/ to /lib/firmware/ on my working system as I not wanted to install 40 odd megabyte of other firmware I not needed.
After moving the files over run the following and all should be ready to use
# depmod -ae
# update-initramfs -u