Recently in one of the SharePoint 2010 implementations we faced the interesting issue of Taxonomy field values in Lists and Pages were not visible for users except Site Administrators.
After spending sometime investigating I found out that in each site collection there is a hidden taxonomy list (TaxonomyHiddenList) which has all the taxonomy field values from the Manage Metadata Terms Database. This list will be synchronized hourly with the Manage Metadata database using the Taxonomy Update Scheduler timer job.
Users don’t have permission to access TaxonomyHiddenList
Give ‘NT AUTHORITY\authenticated users’ read permission to the hidden list located at <sitecollection>/lists/TaxonomyHiddenList