I have always the bug of the limited number of files on my M3 8Gb, even with the last firmware. I'm not alone to have this problem!!
Some guys say that this problem will never be corrected, because it's a hardware problem. H&B with one of their DVD player had the same bug which has never been corrected.
So, until Meizu has corrected this bug of limited files by a next firmware (if it's possible!!!), I advice you to wait before buying M3 8Gb!