@Wiktor_Janiszewski The MongoDB shell is a JavaScript environment and will evaluate its input as JavaScript before running it. This means that
db.cross-app-test.findOne({})
is interpreted as
db.cross - app - test.findOne({})
with the - signs standing for literal subtraction operations.
You can work around this by using either of the following:
db['cross-app-test'].findOne({})
db.getCollection('cross-app-test').findOne({})
This is an inherent limitation when using hyphen characters in collection names.