32GB Flash Drive now has max capacity of 3.87 MB

All I've been using this drive for is the storing of .iso files; albeit over and over again, but even so, I don't see why that practice would reduce the total overall capacity of the drive. I was *amazed* when Yumi said there wasn't enough space on a 32G drive to save a 2.03 MB / GB I can't remember which, file...

Look at my other Externals. I write to them all the time. And they still retain their original max capacity. (4TB)

Any ideas as to how this could have happened?

Thanks in advance,

Pen guin