How to tell the card reader capacity ?

I took lot of photos on the phone and need some organizing, to do that on phone is slow, to do via USB cable via PC slow too, so that I put the card on a card read and do it on PC that worked best, but there's a problem. I got a 256GB card and I put it on a card reader, the Linux PC can read the files no problem, but when I modify the files the changes won't save back and without error, I only know that after I've done hundreds of photos ! I got other card reader that can't even see the card, but the one can read the card can not write back, so what's the capacity limit of card reader, are there standard versions of card readers in capacity, such as 32GB, 128GB, 1T....etc. ?