It sounds like the regular fares have reappeared.

Regular I class fares book into the same fare class and have the same restrictions as sale I class fares. Accordingly during a sale nobody would ever have cause to buy one although in principle you probably could buy one if you really wanted.

From ba.com's perspective, it just looks like the regular fares are not sold. But if you were to check on Expert Flyer I dare say that you would see them there!