Writing files to 128GB MicroSD card fails using an USB reader

I’ve got this 128GB MicroSD card which does not work well when using an USB reader. When writing files it is extremely slow or it hangs.

I only have 1 USB reader so was not able to test it with another one. I did try the same USB reader and MicroSD card on another computer which shows the same behaviour, so i don’t think it’s an issue with the USB drivers.

When using the SDslot in my laptop there is no problem. Also the written files can be read without problems on any device, even when it is almost full. So i do not believe it’s a fake card with smaller actual memory.

First I believed the USB reader was not able to handle big cards like this 128GB card. But recently i bought a 200GB Sandisk card which works without any issues at all using the same USB reader. Also i have many other smaller microSD cards which all work perfectly.

So i believe the 128GB card is broken. What do you think?

if the card is working normally in the SD slot on the computer it is not likely defective. I would copy all the data off and format the card and then retest in the USB reader and see if the issue persists.