And if that turns out to be the case, you can re-format your 64GB drive to FAT32 to make it readable. That’s what we have to do too here in the States. You’ll have to re-load all your music as formatting will erase everything that’s on it, but that’s a small price to pay in order to use the drive in the car.
Another possibility is perhaps your car’s stereo head unit has a database limitation, to where it won’t “see” over a certain number of files. This should also be notated somewhere in your manual or perhaps an online forum for your particular make/model of car.
I’ve got a 64GB flash drive re-formatted to FAT32 in my car and have over 4000 tracks on it and have run into no problems.
Of course, it won’t help your car drive on the right side of the road though.