I thought that I would post this in case it helps out anyone else.
Due to how our load-balanced webservers keep their data in-sync, I need to use a windows network path as my baseDir and thumbnail baseDir.
I'm using the ColdFusion version, so I entered my network path in the config.cfm file as follows.
config.baseDir = "\\myservername\path\to\folder"; ... ... config.thumbnails.baseDir = "\\myservername\path\to\thumbnail\folder"; ... ... config.tempDirectory = "c:\mytempfolder\";