We encountered the same problem today, in about 10 built modules only three of them were marked as built, the rest said "Did not build". We resolved the problem by using "Delete All Disabled Modules" in the left menu for the job. After that everything worked fine again, and even older builds suddenly reported all modules as successfully built.
I believe that the following Jenkins log is related to the broken build (but I cannot say for sure because the server is under quite heavy load):
SEVERE: Trying to unexport an object that's already unexported
java.lang.IllegalStateException: Invalid object ID 3188 iota=4620
at hudson.remoting.ExportTable.diagnoseInvalidId(ExportTable.java:348)
at hudson.remoting.ExportTable.unexportByOid(ExportTable.java:371)
at hudson.remoting.Channel.unexport(Channel.java:612)
at hudson.remoting.UnexportCommand.execute(UnexportCommand.java:38)
at hudson.remoting.Channel$2.handle(Channel.java:483)
at hudson.remoting.SynchronousCommandTransport$ReaderThread.run(SynchronousCommandTransport.java:60)
Caused by: java.lang.Exception: Object appears to be deallocated at lease before Wed May 27 10:51:58 CEST 2015
at hudson.remoting.ExportTable.diagnoseInvalidId(ExportTable.java:344)
... 5 more
I too getting same problem oftenly from last few weeks. all module builds are all success but its not showing green and appears as grey. also as Bahir mentioned these builds are impact on test results also.
jenkins version is 1.528 and Maven Project Plugin version is 1.528