Well, I wasn’t going to publicize my mistake and return the drives, I was going to repair them. The most common solution offered was to return the drive to the manufacturer for replacement. Of the dozens of pages that I read, no one found a fix for the problem. I Googled around and found that many, many people were running into this problem where the drive starts reporting 0 bytes capacity and can not be formatted.
It shows up in the Device Manager as working correctly, without any warnings, for example. Opening the Disk Management component of the Computer Management console shows that the drive is connected, but there is no unallocated space to partition or format. SanDisk U3 Cruzer Micro USB Device Properties