I've got a few each of hermit crabs, snails, and shrimp but they aren't cleaning the algae up very well. Is there any particular reason for this? I thought having a cleaning crew would prevent algae? They don't seem sick, I wouldn't say they're inactive, it's just like they're being lazy when it comes to feeding?

It sounds as if it might be too big of a load for them. For now I'd help them out a bit by gently scrubbing the algae off of anything that's easily accessible and then the cleaners can take care of the places that are less easy for you to reach.

Is the tank new? Because it could have some algae blooms being new but once it's older and balanced out this won't be a problem and the cleaners won't have their work cut out for them!