[TYPO3-mvc] Why is my result for countAll() inconsistent?

[Oliver Salzburg]

In my extension, I want to access FE users. So I went ahead and added
the property/injector to my 2 controllers and, just for testing, wanted
to count the elements in the repository by calling:

    echo $this->frontendUserRepository->countAll();

The output from one controller is 2 (the correct result as I have 2
frontend users set to use Tx_Extbase_Domain_Model_FrontendUser.
But the other controller prints 0 for the same statement.

Given that it prints 0 and doesn't throw, I must assume that the
repository was properly injected.

How can I get to the source of this?

Cheers
Oliver