Component Browser can't display symbol

I have a weird problem that is unique to one project in HDL Design Entry.  If I select a part in the Component Browser in the part table, the symbol does not appear in the browser window and the message "No symbol found for the part."  Yet if I double click on the part table entry, the part symbol will be added to my schematic properly even though the part symbol was not displayed in the browser.  So the problem is only with the browser, not with the library or schematic.

 This problem occurs only for certain parts in the library and only occurs with one project.  Other projects have no similar problems with the component browser.  So it must have something to do with setup and configuration of this project  but I can't find anything obviously wrong.  It only affects the component browser.  In fact I can add the same part on the command line just fine.