Which price tiers a buyer sees on the catalog is determined by the Trading Condition applied to that buyer. Please confirm in this order: 1. In Business Partners → Buyer Management, open the buyer and check which Trading Condition is applied in the Trading Condition section. 2. Go to Business Partners → Trading Condition Setting and open that Trading Condition. In the Price Tier card: if the toggle for that tier is off, the buyer cannot see it; if the buyer should not see a certain tier, turn that toggle off. 3. Also check whether the product itself has a price filled in for that tier: if the product has no price for that tier, the buyer will not see it either.
The same Trading Condition may be applied to many buyers, so changing the toggle will affect all of them. If you want only one specific buyer to see different tiers, please create a separate Trading Condition for them.