what card is it and where did you buy it from?
The other question , was it 64GB to start (?)
And yeah , if its a cheap card , it may not be capable of sustained writes ...
I have a cheap 32GB card , and it is 32GB .. But it simply cant handle being constantly written to and corrupts ..
My guess is , these cheap cards might be coming out of the reject bin ...
Failed to make the grade , thrown in the dumpster , along comes ( ?? ) and pulls the rejected cards out of the dumpster and puts them on Ebay ( Cheap - Cheap )
Believe me , happens only too often ... ( Dumpster Brand products )
Just check out all the batteries sold on Ebay ( from a certain region ) , most of it is Dumpster Grade ! ( Toxic Landfill )
C is being smart in this regard , send there toxins overseas as Products , that after a while end up in some one else's land fill ...
Anyone remember those recalled children s toys that were toxic (?) , who's land fill do you suppose they ended up in ...