Half-open bearing headset? Like the FSA-57E? That one works, but can be a faff to setup as parts don’t play nice.
Sometimes you have to take the stem off, lift the front end of the bike up with two fingers under where the steerer is fitted into the crown, then jiggle all the headset parts into place at the top if its not 100% sealed bearing. There could be a rubber seal falling sideways into the half-open race bearings. Then, when it’s looking secure, put the stem back in place and start to tighten down bit by bit until you meet resistance. Lower the bike, apply the front brake, and tighten the star nut bolt bit by bit, rocking the bike back and forth until play goes. Don’t over-tighten.