Yep, this is a huge issue. In addition, keepers will not fill "lesser" feeders. For example, if I have a tray, barrel feeder, and hanging feeder in a habitat, the hanging feeder will only ever get filled. If I remove the hanging feeder, then the barrel feeder will only ever get filled, despite all the feeders needing to be filled for animals to all have access. In doing the Caldera scenario, I can have 25 keepers and drive myself out of business paying their salaries and they still can't keep the feeders full, just with the base number of animals that you start with when starting the scenario and extra keeper huts built.
That said, this only happens in larger-population habitats, but we're also not allowed to add more entrances to habitats--I'd love to be able to have two-three entrances near to separate keeper huts so that my keepers could access various feeders rather than whatever's closest to the door, as that seems to be part of the issue, too.
Something to remember though is that if an animal eats out of a enrichment feeder it will end up on the ground for them to eat after they interact with the feeder.