Mass compiling the project helped me with a build problem in 8.2.1 (my problem was fixed in 8.5).
Try opening the project and right clicking on it in the project explorer and mass compiling it
(or mass compiling the directory the project is in). My problem was having two classes with the same name
(even though they were in different lvlibs), and I got a bad vi error in the only vi that used one of the classes.
I regularly build my application now because of the various quirks I've run into with the build system
(for instance I can't use the file dialog express vi's in a statechart without converting them to no longer
be express vis). And with regular builds and source control finding those quirks is a bit easier.
Matt W