First off I am not familiar with that coupling.
I am not saying I know the answer to your problem. Just consider this a comment.
Being unfamiliar I do not know if this coupling can handle thrust. I have used couplings which have a shim pack. Since the motor will move to electrical center when it starts it can have a bit of strain on it when it runs. Not good for the compressor or the coupling. Again this may not apply to your coupling. It can be compensated for.