Based on this, you are not the only one with an issue creating the USB recovery media on a Sandisk flash drive. I'm not certain why it would seem it's not working on Sandisk drives, but CherylG recommended getting a non-Windows 8 certified flash drive. The OP in the thread stated they got a PNY flash drive, but didn't specify if it was Windows 8 certified or not. Another user had an issue with a Sandisk drive (granted, it was larger than the max size listed here), but was given a workaround by Pepe999.
Out of curiosity, are the Sandisk drives being listed under Hard Disk Drives or under Devices with Removable Storage?
Reviewing the OP's image in this thread, the Sandisk was added to the Hard Disk Drives category instead of the Devices with Removable Storage. If it is under Hard Disk Drives, then Windows doesn't treat it as a flash drive (where the USB recovery utility gets the drive information) and won't be listed in the utility.