The test center only includes the beta resources, which were gems. You have to actually farm resources on the test center to test imbuing maximum intensity property imbues.
Last year I sent a request to uobugs and hopefully more people request imbuing resources on the test center. Seems like it took 3 years to get all the ML resources and in amounts that were useful. Like they used to give a paltry 100 or so bark fragments so making woodland armor required a person to lumberjack on the test center. So maybe in another year or two the imbuing resources will be available.
-Lorax