I'm taking a look at the Stealthic hair you linked me to (I actually already have this hair in my game!), and it looks like the creator says the content won't work correctly if your game is not up to date or if your game is running in laptop mode. I also have an eyelash mod, and I know that it doesn't work correctly in laptop mode either.
Please check your game settings and make sure laptop mode is not on. Once you've checked that, exit your game and temporarily remove your Mods folder. Go to Origin and right-click on The Sims 4 and "Check for Updates." If there are no pending updates, then right-click and "Repair game," instead. After the repair is done, move your Mods folder back to the correct location and try again.
Let me know how it goes!