I'm not sure if this minor thing is a kernel issue or not and I haven't spent a lot of effort troubleshooting it but...
I have a system with two sata hard disks and, usually, one USB flash drive plugged in. Occasionally, I plug a second USB stick in for backing up the primary one.
All connected drives mount and work fine (hence the minimal troubleshooting effort) but conky (the conky_plus extension) never recognizes "sdd", the second USB stick, as being mounted. I've always assumed it was some issue with conky, and I still suspect so, but if you could eliminate the possibility that it is some kernel configuration setting, I'd appreciate it.