Frank Goossens on "[Plugin: Autoptimize] JS not optimized or compressed"

that's because it has a nonce in it;

data: 'action=nice_appointment_form&nonce=ec22ac7a0c'

nonce's are random strings that are used to secure data/ form submittal, but they change regularly. as those strings are random, changing regularly, AO excludes them from optimization to avoid the nonce's from breaking the cache, meaning your cache size would grow too quickly.

hope this clarifies,
frank