Question about SanDisk Ultra Dual Drive Luxe

I recommend testing the stick with the programme H2testw 1.4, a free tool from heise.de. It writes the USB stick completely with test files and then reads them from the USB stick. If errors occur during reading, then you have proof that something is wrong. For example, practically all USB sticks ordered directly from dealers in China are simply counterfeit. With the tool you can easily detect this. Sometimes such counterfeit sticks make it to Europe, so it is always advisable to test a newly purchased stick quickly with the tool. It doesn't have to be a fake, but this way you can be sure that what you buy can be used without any problems.

Bought this stick too and it works without any problem. at least tells me 122GB available. ;)
I have not tested it though. I've never done that before, and I've already bought a few sticks. from 128MB to 128GB now. At that time 128MB were as expensive as 128GB today. ;)

Have you ever checked if it has partitions on it? Which OS do you use?

I recommend you proceed as described by Stardustone. For your information: My stick works perfectly and has the specified 128 GB available.