Yeah, more than likely a power issue. If I am right, it’s a 2.5″ so there is a chance it could work (3.5″ in my opinion never work off of USB power, most will come with an external powersource).
With 64GB not being an extreme size for a USB stick and 64GB being plenty space to bring your music for that gig, I usually advise to use sticks, not HDs. An alternative you can try is getting an external SSD, with 256GB now reasonably prices, this is 4 times a stick.
USB hubs don’t work well with CDJs, so a powered hub is not an option either.
Some external HDs come with a special cable that has TWO USB connectors, so you can use the power from two USB ports. CDJs only have one USB port, so no help there either.
If you really want to test if it’s a power issue, get one of those split USB cables and plug the power only plug into a usb wall outlet adapter, the other goes into the CDJ. If it works, you can decide to use it in that setup.
Still, my advice would be to use sticks and “limit” your gig collection to 64GB. That should work everywhere.
As far as FAT32 format is concerned, this is the most common format and should work with both Mac, Windows and CDJ(like) gear.
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