I'm not sure how to answer the "how is it mounted" part; I just plug it in via the 30pin/USB cord (it's an iPod classic 7th gen). However, ejecting the iPod did make it work. I tried disabling "enable disk use" in iTunes to see if that made a difference, it didn't, and maybe later/tomorrow I'll try with my iPod nano (also 7th gen) to see if that is different and let you all know. I tried to close iTunes to see if having the iPod mounted, but iTunes closed would make a difference, but closing iTunes also ejected my iPod so I couldn't say for sure.
Thank you. Seems stupid to me that I can't import photos with an iPod attached, but it's nice knowing what the issue is. Is this something that's fixable or just a fact of life I'm going to have to put up with?