I know this thread is a little old but I just installed the Z140BH and am using a 32GB card with no problems. I am a little disapointed that the unit will not show the artwork but it plays just fine. I have a 64GB on the way and will reformat it to use FAT32 and will update the outcome.
UPDATE: I received my 64GB card and formatted it as FAT32 and it worked perfectly!
I had to use gparted as windows will not format anything over 32GB as FAT32.