I highly doubt it's supposed to give you full stamina.
Wouldn't mind some more stamina, though. All those trained soldiers and they can't sprint very long.
If you play offline, refill DOES refill stamina. It has been an online-only issue since the beginning so I'm guessing thats what this means.
But, it shouldn't refill. Everyone would be sprinting back and forth, tunnel-waring on certain maps, and it would be like cheating. Conserve stamina. Maybe increase the stamina pool.
After using the corrected refill mechanic in beta 4 for a while, I can confidently say that it's nicer and does not create any issues. If you're getting a refill, you're getting full health, might as well get full sprint too.