https://jira.mongodb.org/browse/MONGOID-4914 implemented delegation of association#find to Enumerable#find to filter the association in application process space.
The same can be done for top-level model classes.
Example code demonstrating the problem:
Here I expected the block to be called for each band and the first band to be returned, but I got nil and the block was not invoked.
See also the discussion in https://github.com/mongodb/mongoid/pull/4802.