There is a known issue regarding these players’ tendency to display “unknown artist” or “unknown album” even when Windows Explorer, or Media Player clearly reflect the correct artist and or album of a particular song when the unit is connected via the USB port. This issue appears to occur randomly and even the most recent beta firmware (version 2.2.5) has not resolved it.
This issue is actually related to the number of files stored on the device. When using MSC mode every 100’th file uploaded to the device will appear as unknown artist. This appears to be some sort of off by one error in either the ID3 parsing routine or the database creation routine. Breaking large groups of files across multiple directories does not appear to solve this problem.