I'm using the Thinkpad X380 Yoga.
$ lspci | grep Card
02:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS522A PCI Express Card Reader (rev 01)
$ uname -a
Linux TPx380 4.19.6-1-MANJARO #1 SMP PREEMPT Sat Dec 1 12:21:26 UTC 2018 x86_64 GNU/Linux
The SD card type "SDSQUAR-128G-GZFMA" is working just fine with the internal card reader.
But the card type "SDSQXA2-064G-GN6MA" doesn't.
When I insert the card I get the following error:
mmc0: error -110 whilst initialising SD card
When I use a USB card reader, the card is detected and working. I have tested 3 different cards of the same type and I tried it on both, my Arch Linux and Manjaro installation but the behavior is the same. Couldn't test it on Windows though.
Is this a bug or am I doing something wrong?