(also affects 17w43b)
What I expected to happen was...: the function should run
What actually happened was...: "Unknown function: namespace:folder/function"

Steps to Reproduce:

1. Create a new world (or open an existing one) in 17w45b
2. Create a "functions" folder in [world save]/data
3. Create a "namespace" folder in [world save]/data/functions
4. Create a file called "test.mcfunction" in [world save]/data/functions/namespace
5. Add a command such as "say test" and save the file.
6. Back in minecraft, run the command /reload (note that in the case of invalid commands it still provides no feedback, even though it's supposed to display an error)
7. Run the following command:

   /function namespace:test
   

8. Observe the output:

   Unknown function: namespace:test