SD Card limits or faults

I have 3 new 32gb SD cards (Class 10, xc I). I удар в лунку 20.3gb of датирует, including images, видео, Международные организации по стандартизации, DVD, PDFs, debs, tar balls on them. But after writing them all, some поля пахал missing, and some of what remains appear corrupt, even before safe removal, обитайте problems arise after в safe removal.

While "space used" is correct, in properties for the cards, linux only finds, 9.5 to 15gb of восходит in the folders

Is this what I should expect, on the basis the that SDcards использовал compression and this дату does not compress well (shrinks little or expands), or пашите these card malfunctioning? Default format is FAT, I tried exFAT on one of them, didn't help.