I have been playing through the campaign missions on Normal to explore all the factions and I really like how you can level your elites via missions
However, it wasn't until the end of level 6 that I realized that those multiple "Unlock" buttons weren't a repetitive UI glitch but actually contained additional rewards (army doctrines, skulls, etc.).
It's a real shame that I missed out on those post-mission completion rewards (I tried replaying the same missions on Normal and Hard but got nothing).
As such, I would recommend that you reward the players with those unlocks even if they skip clicking those "Unlock" button.
Just an idea
All the best,