You will get this blank screen if the database specified in the data source does not exist. The test button in the data source will succeed regardless of whether the database exists.
A way of checking whether the database exists is to use the show collections
command. To do this, use the mongo shell to connect to the target MongoDB server (i.e. the one specified in the data source where the schema editor is blank). For example:
C:\Program Files\MongoDB\Server\3.0\bin>mongo > use faa switched to db faa > show collections Mersenne_Collection_Metadata Mersenne_Collection_Metadata1_3 airline system.indexes > use madeup switched to db madeup > show collections >