i got sent a load of cherry shrimp and i know discus eat these as tried them before, but with these cherry shrimp was a very large anamo shrimp easily a bit bigger than a full size guppy, would the discus eat that??
If it could fit in the fishes mouth, it would probably end up there sooner or later is the easiest answer. A large Discus could fit an adult Amano in, so if you have Adults of each and you are missing a few Amano shrimp, I'd say you now know where them went